I would not make too much effort on Moles if you are moving to VS 2012 and intend to use fakes. There is enough difference to mean you will be doing a good deal of work.
There is some notes on my blog http://blogs.blackmarble.co.uk/blogs/rfennell/post/2012/03/23/Now-that-VS11-has-a-fake-library-do-I-still-need-Typemock-Isolator-to-fake-out-SharePoint.aspx
But the BEST place to look for details how the differences between moles/fakes and other frameworks can be found in the ALM rangers guide on the subject http://vsartesttoolingguide.codeplex.com/releases/view/102290