I'm trying to upgrade my system from Fedora 8 to Fedora 9 using apt. I've been successful doing this from FC4 to FC5, 6, Fedora 7, 8. Without any issues.
First of course, I've had to replace sysvinit with upstart. The issue right now is that apt is returning a weird dependancy problem.
WARNING: The following essential packages will be removed
This should NOT be done unless you know exactly what you are doing!
authconfig newt-python (due to authconfig) rhpl (due to authconfig) kudzu rpm
rpm-libs (due to rpm) vim-minimal
Like I indicated above, I haven't had a problem upgrading sequential versions from FC4 to Fedora 8.