woo, great news, especially about fennec!
when can I do "apt-get dist-upgrade" then? huh huh, please please???
You should know that fresh installs are the way to go, though you probably could now if you find the repos.
dpkg/apt is largely bullet-proof once set up right as long as the distro is fairly stable and you're not making massive changes to kernel and glib.
the only reason for a fresh install would be to get the updated kernel, but now we're all multi-boot that's not needed.
the only time it's gone a bit wrong for me was when debian changed from 2.4 to 2.6, a new gcc and glib. but then I did try to take a short-cut and I was a n00b!