As others have said I wouldn't recommend testing as it doesn't get security updates, however I personally run sid (unstable) and have for a long time now. At least since 2020 if I recall, it does occasionally break, albeit anecdotally less than my friends arch system, can't comment on if that's the distro or just our individual setups. The main reason I run it is because I like debian, I'm very familiar with apt, with its initramfs tools, with all of the debianisms but I wanted something rolling. I tried arch but it just wasn't as comfy for me personally. That being said it is a bit like hard mode, there is no arch wiki, if you don't do heavy customization that might be ok, sometimes I've wanted to tweak my initramfs and while I know the debian generator better than arch, there's far less easily accessible documentation on it. In general it's been such a good experience that I basically stopped distro hopping, it's been my home now for a long time but I know I'm in the minority with that so take it as you will.