I just did an in-place fc6-to-f8 upgrade and it went pretty smoothly.
One gotcha was I had to adjust the qjackd settings thusly:
1. Change "Server Path" on qjackctl's Setup page to "pasuspender jackd
--". This suspends PulseAudio so it isn't hogging the ALSA ports while
I'm running jackd.
2. Change the "Interface" setting to "hw:0" from "default". jackd
wouldn't start up otherwise. Any idea why?