The migration wizard is a bit of a nightmare. I have never known anyone to actually use it for production code. It is likely you will have to start fresh you know? :-/
In your "new" project, can you see the two files AppDelegate_Pad.h and separately, AppDelegate_Phone.h ?
Do you in fact have TWO xib files MainWindow_Pad and MainWindow_Phone
Open the two xib files (IB) and look at the App Delegate in each. Click command-4 for the identity inspector. Eyeball the class in each case.
Does it look correct or are they flipped? Hope it helps!