I don't have any input on your download direction... But I wanted to share some drive links.

Folks on datahoarder love these drives.. Dell Exos X18 18TB SATA 6Gb/s 7200RPM 3.5-inch Enterprise HDD - ST18000NM002J (Renewed) https://a.co/d/9LeBkx7

And recertified drives / server pulls on https://serverpartdeals.com/collections/manufacturer-recertified-drives

Might be a cheaper couple of options for expansion.

Sorry I can't help with your question, but I wanted to ask what features you feel Jellyfin is missing that is keeping you on Plex? I've made the switch, and actually like Jellyfin better.

Real-Debrid is great. I use it for streaming, but I honestly use it more often for pirated music software downloads. Instead of having to go through 30 Rapidgator or Mega links or whatever bullshit, it handles it in one place.

You can test the waters and just add a debrid service as a download client to your Arr setup with RDT-Client. It works just like a regular torrent client in that case.

Real Debrid is awesome, I have a jellyfin server setup but it's only for friends/family and Anime (because it's hard to find via scraping debrid.) If I want to watch any live action movie or show I do it via kodi and seren, that way I can watch 4k hdr bluray remuxes without having to store 50GB+ files for something im gonna watch once

I can't comment on questions 1, 3, and 5 but I have been using Real-Debrid for around four years now (through Kodi mostly because I don't want to have to manage a huge server again, occasionally I download directly to watch later/on a different device/non-video stuff) and I've been pretty happy with them so I'll answer from that perspective.

Quality is great. As you mentioned in Q4, it works via torrents so if a torrent exists you're free to grab whatever you want. You can stream or download from RD once it's been cached by them. Even 50+GB Bluray remux streams fine directly from them. As for file naming, in the thousands of downloads I've gone through, I think I've come across two incidents where something wasn't named properly and I ended up with something I didn't expect but I believe both of those were Kodi issues, not RD. One was a movie where I got a foreign movie of a similar name and one was a TV series where it kept trying to play the wrong season/episode. In both cases I was able to just manually add the torrent/magnet and RD had it fully downloaded basically instantly or I was able to manually select another file in Kodi. The file names are what you expect with a torrent though with the title/year and all the quality and codec info in the filename so it's hard to get the wrong thing. I don't think I've ever come across deliberately misnamed files. It would get nuked pretty fast, trackers usually take stuff like that pretty seriously.

Assuming something is relatively available RD seems to be able to grab it very quickly. Like as fast as the page refreshes after adding the torrent/magnet. You also download very quickly from them; I typically see over 100MBs down over my wireless connection in a house with several other people using our connection which is pretty much fully saturating our bandwidth lol. Occasionally I have had issues getting something, but like with most things, the older and more obscure you get the harder it is to find sources for. In that case you may want to be on certain trackers. This is kind of why I like Kodi because there are plugins that focus on different types of media and some may have better luck finding, say, old 90s cartoons while others are better for anime. Once it gets added to my debrid I can go back and grab it/rewatch later. But for more popular stuff, I typically just use one of the big name public trackers. RD grabs it and I get it securely and privately from them. I've never bothered with a VPN and have never had issues.

One thing that I didn't see mentioned was downtime. Occasionally RD has had some downtime. If you've ever been on the addons4kodi subreddit you've probably seen the posts with people freaking out about it within minutes of it going down. Downtime is typically minimal and usually back up within minutes to a few hours. In a few instances (like maybe twice?) it went down for like 12 hours or longer? Not really sure, if it goes down I just find something else to do and check later in the day or the next day and it's back up. RD has also been known to compensate days worth of service for hours of downtime which is pretty nice. I haven't heard the same about Alldebrid or Premiumize.

RD also gives you tokens based on the service package you buy (called fidelity points). 1000 points will convert to 30 days of service. I buy 180 days at a time which is currently around $17.33 USD and I get 800 points, so buying a year (~$35) gets me an extra month with points left over. Then the next several 180 day purchases also get extra months with them.

I've used real-debrid in conjunction with the seren add-on for Kodi for years. I have the same setup on all my PCs, my phone, my Chromecast. I would say it works identically on everything but I had playback issues using the Kodi app on my Xbox (well documented issue related to that system)

1. No, you just scrape the debrid cache on demand upon selecting an episode/movie, as long as someone has already cached that release it'll just start streaming. If not, you can add it to the cache inside the add-on, rescrape and try again
2. There's no encoding happening, it's just direct streaming whatever release you selected. For release of duplicate titles when you search it will show the IMDb/tvdb thumbnail and you just choose the one that looks right. The only releases that weren't exactly what I was looking for was when Barbie just came out and some cam rips were floating around, the first result I scraped was for the animated Barbie Netflix series. No porn, I'm confident enough of that to have set this method up for my mother also.
3. Sounds redundant. If you wanna try this method for ease of use, a simple netflix-esque experience for any content, there is no comparison. If you wanna spend time watching your logs auto scrape the episode you're waiting to drop, this isn't the method. The only mechanism needed for routing your search to a matching file in the debrid cache is scraping a magnet link (via a search, or trakt recommendations etc) which matches a file previously cached on the server. "It just works"
4. Not if you're using a standard implementation with A4kScrapers. Google how to set up seren on Kodi. You may run into some P2P release for older stuff, for most people this is totally fine

All in all as someone that has pirated music, tv shows and movies for several decades now it actually aggravates me how user-unfriendly the Plex/emby/jellyfin experience really is. I can certainly understand people getting enthusiastic about a new hobby of library management, but that shit gets old and I just want to watch my shows. The only reason I can imagine why people don't do this is because it costs money. I struggle to imagine how these same people aren't already paying money for tv/movie content and getting way less value/$ to boot.

As a honourable mention I authd this setup on my mother's Chromecast to my real-debrid account, and we have no issues both using it simultaneously. However, one time when I was downloading a torrent using the debrid on my PC with VPN, while streaming on my TV without VPN, and my mother also simultaneously streaming in a different city, it booted us all off and I had to reauth. No issues since, mum calls it the dodgy box

After short research, I think, that the change of takedown is bigger with debird as with usenet due to the decentral nature of the usenet. On usenet, your provider may ho down, but you can just config a new provider and continue to use your setup as is (same media manager, same downloader and same Indexer), with debird, it seems to me, that it is a very centralized service, that in theory can be nuked at any time. Please correct me, if I am wrong

~~I~~ SWIM was running Plex with Usenet and honestly, ~~I~~ SWIM was disappointed with the state of Usenet servers these days. ~~I~~ SWIM switched to Stremio, plus Torrentio, plus Real-Debrid, and it is amazing. You don't need any storage capacity. You don't need to set up any downloads or know what you want ahead of time. You just use it like you would any other streaming service, except almost anything you can think of is available. The only drawback is that 4k is rarely available. But 2k is almost always available, and that's good enough unless you are going to watch something visual like Avatar, Way of the Water. If that's important to you, then just rent those particular visual spectacular movies, and stream everything else. The best part is that Debrid is only about $2.80 per month, vs $15 for a Usenet server, and another $30/year for a search engine. There's a good guide for the whole setup on Reddit. Something that might help you with the setup is knowing that it's stored on the cloud. So you can set Stremio up on a PC where it's easy, then install it somewhere like Nvidia Shield TV or Chromecast 4k, login, and you're good to go. Hook it up to your 4k home entertainment center, and paaartay!

What is your storage situation currently? Just trying to figure out why you think expanding it is expensive, because hard disks have been getting cheaper. Especially used "enterprise" SAS drives - the 12TB drives can be had for under $100. You'll need a $40 HBA card and $10 breakout cables as well.

I bought this a few months back when my 8 terabyte ran out of space. It was on sale for like $204 shipped. Given how these things fluctuate, I would not be at all surprised if it went on sale for that again at some point in the future. You might set up like a CamelCamelCamel Alert for something like this.

Western Digital 16TB Elements Desktop External Hard Drive, USB 3.0 for plug-and-play storage - Western DigitalBWLG0160HBK-NESN https://a.co/d/6rA4a6i