Had really trouble to get it working the first time (maybe because my 2.0.6 had market install, a2sd, root, etc), but downgrade made it even worse, so I did a hardware reset and went back to dealerupdate091210_.zip, then going to every upgrade available.
Surely bothersome, but I wanted to play safe

Now I have it up and running on 2.1.1 gamma and presently I'm quite fond of it, although I don't get the market running, the old tricks don't work.
All backed-up apps work, WIFI was no problem at all, and the new UI is qiute OK.