I would need some more info on why it gets stuck immediately after booting...
If somebody could build a debugging build (I can't publish for the moment) we could trace it down...
It could have something to do with the new i7 cpu starting procedures...
I'll check it from here and if anybody can test it with a serial debugging console on a debug build... please do... everything is working fine for me...
you can still set the model name with macmodel=MacPro2,1 e.g. or with -nomacmodeloverride boot arguments (to disable it)