Some thoughts about debates:
1) General election debates will either have no audience or a hushed audience. Gingrich will not be able to work the room like he did on the Fox & CNN debates.
2) Obama is a much better debater than anyone who has been on the stage with Gingrich.
3) As much as Gingrich can fire up the GOP base, he will also fire up the Dem base and alienate independents.
4) Debates have less effect than most people think, and I'd think an Obama/Gingrich debate will have minimal effect. Both are well known public figures that the vast majority of the electorate have already formed thei opinions about.
"It does me no injury for my neighbour to say there are 20 gods or no god. It neither picks my pocket, nor breaks my leg."
-- Thomas Jefferson