Running sid is an option, but the amount of fiddly Debian magic you end up needing to learn when it breaks is IME not smaller than the effort of setting up a mostly-unpatched rolling-release like Arch (and I’m sure there are other options). Given that e.g. Arch’s packaging is simple enough it’s no big deal to package even your personal collection of handy scripts (and so the system does not develop funny-looking mold and bits of mystery food all over the place), I don’t really see the point. Just don’t update it when you’re on a deadline.
You can see that my arguments here are to a great extent a matter of preference and personal circumstances, though: do you have a reliable Internet connection for troubleshooting? do you prefer a more solid system that you have to fight and that fails badly but rarely or a less solid one that fails more often but in small ways? does getting locked out of the graphical environment every couple of years count as small?
(Offer not applicable on machines with cursed hardware like nVidia or Broadcom.)
the other subtlety is that security updates come later to testing than they do to either stable or sid, but this can be mitigated: https://gist.github.com/khimaros/21db936fa7885360f7bfe7f116b...