Firefox on Debian stable is so old that websites yell at you to upgrade to a newer browser. And last time I tried installing Debian testing (or was it debian unstable?), the installer shat itself trying to make the bootloader. After I got it to boot, apt refused to work because of a missing symlink to busybox. Why on earth do they even need busybox if the base install already comes with full gnu coreutils? I remember Debian as the distro that Just Wroks(TM), when did it all go so wrong? Is anyone else here having similar issues, or am I doing something wrong?
The fix comes to sid first. (Not counting experimental.) The right way to do it is to run mixed testing/unstable with apt-pinning so that nothing gets pulled from unstable unless spcifically requested.
That said, stable with Firefox from Mozilla's site and Neovim built from sources and gpack'd into deb package runs perfectly fine with much less hassle.