Never heard of him.
Larry Sabato was one of my professors at Georgetown in 1992. He was an OK professor; he seems to have become more famous in recent years.
He teaches @ UVA and while I don't agree w/ everything that he wrote, he makes a reasonable argument. Also, he's very evenhanded and doesn't mind taking some jabs at the Dems (see his comments about Kerry). He's not someone who can be dismissed as a left-wing partisan b/c he isn't one. Agree or disagree w/ him, but he does his homework and provides some good analysis.
Not that I agree with his analysis, but he is highly respected in the world of political science. I was a poli sci major and I read a few of his books.