"What do the pros" shoot depends entirely on what division/sport you're talking about. For USPSA it breakdowns roughly like this:
Open Division: Everyone is shooting some wild race gun built on the 1911 platform, except for 2 guys with Tanfoglios. You're also starting to see more and more "Open" Glock 35s, and with S&W releasing a .40 S&W M&P pistol with a 5 inch slide, that should start showing up as well.
Limited Division/Limited-10: Again, a lot of super trick 1911 style guns with double stack magazine wells will be the most common guns in this division; but Dave Sevigny and others have been making inroads with Glocks and other polymer guns.
Production: At the top levels, this division is dominated by Glocks and M&Ps, although Ben Stoger shoots a Beretta Elite IIA; the Glock 34 and M&P Pro 9mm are very popular here.
Revolver division: 99.9% of shooters at the top level are shooting S&W 625s in .45 ACP, although you'll see one or two guys running a 686 cut for moonclips.
Single Stack: 5 inch and shorter 1911s only are the only guns allowed in Single Stack division. Originally this was a league of its own, but it was acquired a few years ago by USPSA.
Mind you, this is not at all a representative sample. At the club level you're going to see every type of "division legal" firearm under the sun.