I tend to distrust used/refurbished tech -replaced for a reason sort of thing

I would never buy refurbished unless it was the only option. You basically paying extra for someone to repair a broken phone (possibly with inferior parts) at that point, whereas used you can find phones that have babied by their owners with a case and screen protector and have nothing wrong with them. In Australia, most newer used phones are being replaced due to an upgrade because the owner reached the end of their plan and can essentially move to a newer phone for "free", or because they damaged something like the screen and they'd rather buy a new phone than repair their current one. With the latter, the cosmetic damage is usually clearly visible and described by the seller and is therefore easy to avoid. For older models, it's usually just a normal upgrade.

Water damage used to be a bigger risk with secondhand phones, but these days so many have decent waterproofing that it is practically a non-issue. In terms of just general risk, used phones are really low in my opinion. I think people are a little too obsessed with warranties and have this doomsday scenario in their head where they buy a used phone and it just instantly dies. It's just not realistic at all, phones will last a very long time as long as they aren't exposed to extreme conditions. Just be patient, be smart and research the phone and the seller thoroughly before buying and you basically can't go wrong. People are really sleeping on used phones, and electronics more generally. They are great value and a much better choice ethically.

EDIT: That's a sick looking phone by the way, I wish there were more made with that type of colour scheme.