I've done that as well. These days I run on the beta channel. Haven't had a lot of crashes with either. With the beta channel, I tend to click the restart to update button once a week or so.

On Arch linux, I ended up installing the tar.gz from mozilla and I let the browser update itself. Arch packaging is kind of redundant for this. It just adds time and middlemen that I don't want anyway. If there's a critical security update, it just increases the amount of time it takes for that fix to get to you. Regardless of whether you use stable, beta, or nightly. It does add a bit of hassle for e.g. getting a menu item with the correct icon in Firefox. I do the same with a few other things that know how to self update.

That should work on Debian as well. But a .deb package from Mozilla is nice of course.

I once used nightly for months to get a new feature earlier and 99% of the time it was as stable as the normal build.