I've upgraded a copy of my FFP2 to FFP3 for "gamma testing"
I noticed that the urlclassifier2.sqlite file is not deleted upon upgrade.
You might want to delete it yourself as it's function is merged into urlclassifier3.sqlite in FF3.
As urlclassifier3.sqlite looks like it's going to be huge (currently at 27MB, 50MB expected) getting rid of "2" might help you a little space wise.
I am currently running this on a machine at work w/ high speed internet accesss.
I'm curious to see if I can then just copy the urlclassifier3.sqlite to my home test install and save myself the initial download.
NB FFP"2" will continue to be my main browser for a while as many of my addons are not upgraded. I will however be "gamma testing" various setups of "3" till I feel compfortable, but that might be a while.
So far I don't like it, for all the reasons mentioned elsewhere.
Tim