@Linux @debacle I also routinely do apt dist-upgrades on my debian testing (and every time a new stable is out on my debian stable machines): I have installed a lot of packages, including non-free firmware.
notably I never add 3rd party repositories, only the official debian ones; I almost never have held packages, and I can't remember running into dependency issues on stable. On testing sometimes it happens that dist-upgrade would remove some package I use, but in that case I just wait a few days before trying again and it usually has been fixed.