[vbernat]

Many DD are running unstable, so it should be non-breaking enough for most people. The most common breakages are file conflicts. It is a shame we didn't fix such issues yet, as it is a bit difficult to fix the problem, but having testing as an additional source and rolling back the problematic package should fix the issue. I don't remember any other kind of breakages (other than upstream regressions, but this is a rolling release) for the past five years. If you tried unstable 10 years ago, this is now vastly different.

On the other hand, I remember Arch transition from readline 6 to 7 making the system unbootable (2016) if you did upgrade at the wrong moment. I don't know if package containing libraries are now versioned to avoid such issues.

I think the main difference you get by using Arch is AUR (we don't have that in Debian) and, I think, more fresh packages (mainly because it easier to package for Arch than for Debian).