...the only way I knew how to revert back to KDE4.5 was to look at PiSi history and revert each update change to its previous version...
This is how you do it;
sudo pisi hs -t XXX
XXX is the process number of pisi actions ("-t" stands for "takeback"). You can see the history and numbers of pisi processes by "pisi hs" command. By doing this, you can see which process has ruined your system, and you can take it back.
"pisi hs --help" for more information.
By the way, I am totally on the devel repo for a few months, and I am very much satisfied with the speed of KDE 4.6.2. I also did the same to our laptop at home, the machine just got wings!