There is nothing in post election data showing McCain picked up more votes from independents and moderates than 0. McCain's nomination lost over 11 million votes in conservatives who stayed home and in write-ins, and losses to 3rd party candidates Barr and Baldwin.
I worked on the McCain campaign and the argument that he pulled Ind and Dems in any useful margin are a commonly held fallacy.
I don't see that it will ever change because we won't ever agree on a person.
Oh, well, we'll continue to lose elections but feel good about ourselves.