The upgrade to KDE 3.3.1 went O.K. for me, but, with one exception, I followed the very conservative procedure outlined by XavierP in another thread (that I believe you started, actually):
EXCEPTION: I downloaded my KDE 3.3.1 packages from Current rather than from the download.kde.org site. There may be no difference; I didn't check carefully to see.
NOTE 1: I had already done all the Current changes through Oct. 25 with the exception of the KDE upgrades, which I postponed for fear of goofing something up.
NOTE 2: In addition to XavierP's instructions in the second post of the thread, there's a followup post from XaxierP further down the thread that mentions adding "arts" as an argument for removepkg. I didn't see this, but I didn't have any problems, perhaps because I had already upgraded arts when I moved from 10.0 release to Current.
All that said, I don't see a particular performance increase in KDE 3.3.1 vs. KDE 3.2.x. But I have trouble resisting upgrades, for some perverse reason. After I get burned badly, I'll probably be more conservative. I do try to take the most conversative upgrade approach, however, by following the instructions from ringwraith and major.tom here:
So far, so good. I hope it goes well for you, too.