Two completely different eras in politics. In 2006, Republicans got their butts handed too them and a lot of people that were trying to help G.W. Bush went down in flames. Gingrich was lost since out of the picture then.
I just base my view on electability. I think its hard to compare years but he was thumped in 2006 if it was close I could believe times have changed but he lost badly and six years is not enough time to change the negatives that caused voters to chose the other guy