Duff-Man says...if it's not I'm sure someone will start yet another pointless class-action suit against Apple....what am I saying....they'll do it even if it was built from the ground up.
You know - building from the ground up isn't just about the UI - that's something they'd want to try and keep at least some familiarity with (unless there are severe problems with it)....it's the unseen under the hood stuff that usually makes a bigger difference and usually goes unnoticed (unless you're a forum veteran that uses the term "snappier" I suppose)....oh yeah!