I installed XFce 4.6.1 from the testing repo today. Sigh of relief!! I really can't stand the KDE desktop--not version 4 or anything before it. Now with XFce as my desktop, I can do more testing because I got too irritated to continue with KDE on beta 4 after an hour a day or so. XFce is working fine so far. I didn't install any XFce plugins yet. May do a few over the weekend.
I'm very happy with the performance on this old 1.3 GHz Celeron. On this computer I don't notice any speed difference between Light, Standard, and now SOHO.