As for the reason to switch: that's something I can get behind, although you could also just slap Proxmox on it an do all your experimenting in VMs; at least that keeps the server itself running as smoothly as possible, while not limiting you in your learning experiences.

As for btrfs: it most certainly does have RAID functionality. RAID5/6 is considered unstable (although I've heard/read from plenty of people who have great experiences with it, provided you don't run into the edge cases), but I'm sticking with RAID1 because I don't need to run the risk, and I'm not sure if waiting for a checksum calculation whenever something does go pear-shaped is going to do a whole lot of good for me.

Anyway, as for my setup: an HP Microserver (an oldie, a Gen8 with a Xeon switched in) running Leap, powering a few VMs, a collection of Docker containers, and a few "native" services (nginx, PHP, stuff like that). The root fs is a single SSD (btrfs SINGLE with some directories having a flag to disable COW), and there's a data pool of 3 spinning disks (2x2 and 1x4GB), 4GB effective, that contains "data". Most of it is setup with Ansible these days, hence no real use for YaST on that machine for me.