Just switched 1.2.80 to 1.1.99 DE, currently booting power kernel, stock, & Nitdroid U12/May as well. As it comes up every thread - I followed mostly these instructions (http://talk.maemo.org/showthread.php?t=73146) to get it multi-booting.

A bit slow, likely on account of the SD card. DE is better than the 1.2.80 version, in that it detects screen size properly. Didn't poke too much at it, but was able to make a phone call to the wife and take some pictures. SMS program crashed & wouldn't close so didn't get to try. Also, battery wouldn't charge. Long way to go...