I've been running testing on multiple workstations for over a decade and very rarely have issues. Just avoid updates right after the rollover to stable and you're good.

I have been running sid (unstable) on my desktop since 2013. I've had maybe 4 issues in all those years. This is through multiple ram, diak, power supply, motherboard upgrades. It just runs fine.

I have been running unstable for over a decade testing is just fine install apt-listbugs and apt-changelogs and keep an eye on mass removes when you do an upgrade and you will be just fine. also timeshift is your best friend.

I've been running testing for quite some time. Runs well. Sometimes some smaller hiccups during the freezes. They don't promise you'll get security patches on time (with anything but stable). Otherwise nice rolling distro. I'm occasionally mixing in packages from unstable.

I would say testing is okay - I have used the same install on my desktop continuously since early 2022. It's the same as usual - some packages might disappear during transitions and then reappear, like FreeCAD. When that happens, I just use the Flatpak. I think the only major issue I've run into with current testing was some of my systems got borked during the time_t64 transition and I had to chroot in and fix them, but that got sorted out months ago and is probably the only huge issue I can think of.