Interview with Colin Bonstead, the technical director, from November 29, 2011. He doesn't say anything about Wii U hardware being more powerful than the current gen here. He said they got the game to the point that it was "at parity with other platforms" in time for E3.
Then general manager David Adams says "It's all the same assests from the normal build, we didn't really do much to it".
http://www.youtube.com/watch?feature=player_embedded&v=Tl3HGOsAlx0#!
magash owned so hard.