obsessedwithrc, I have shot USPSA Limited 10 with two Glock 22s and currently working the trigger on a new M&P45 to shoot USPSA Limited 10 and IDPA also.
There were some shooting Beretta 92's at matches when I started match shooting with 1911/Sig 226 some 15 years ago, but most switched over to Glock platforms, like me.
I would highly recommend the Glock platform as we have done many comparison pistol shoots (total up to 35 different make/models) and Glock 17/22 typically come out on top for best stage times/accuracy of double taps over other factory stock pistols. I also found new shooters tend to shoot more consistent and get tighter shot groups with Glocks than others brands/models.
One primary reason why Glocks are popular in match shooting is that it has very short trigger reset (amount of trigger travel back to reset the striker) which allows you faster double taps. As you shoot matches, you will find that best scores often come with faster times. Accuracy can be obtained with most high-end semi-autos on the market, but not all come with short trigger rest from the factory. You can get shorter trigger reset on M&P pistols by doing a trigger job or replacing the sear. Most match shooters will significantly improve their accuracy within a few months of match shooting. However, their stage time decreasing takes more time and proper deliberate practice.
If you start out with G22 over G17, you can drop in a $100 Lone Wolf 9mm conversion barrel and be able to shoot the cheaper 9mm rounds for practice or actual matches. You will need several magazines to start (like 5) and factory Glock magazines are cheap ($20 from CDNN), durable (dropping them on the ground for mag changes won't hurt them) and easy to maintain. There's a ton of factory/aftermarket support for parts and accessories (trigger kits, holsters, mag holder, springs, etc.) and they are priced lowest of all pistol models due to higher volume customer base.
Another benefit is that I don't hardly have to clean my Glocks to be match ready. With my match 1911 with tight fitting match components and Sig 226, I had to keep them absolutely clean and lubed to be trouble free on match day (about 30 minutes work). With my Glock 22, all I really need to do was field-strip to clean the barrel and lube the four slide rail points and barrel contact point. That's it, and I am ready for the match. I have shot up to 2000-4000+ rounds during practice and two matches with just the barrel cleaning/slide rail lubing and had no problems.
M&P models will require trigger job or sear replacement to match the factory Glock triggers for comparable double tap speed and groups. M&P's have better ergonomics (shorter/better reach to mag release and slide release) as I have to tilt the Glocks in my hand to reach the mag release. M&P's are also a great platform and I see more and more of them at matches. You can get 40-9 conversion barrel also for M&P40 to shoot 9mm.
If purchase cost is an issue, I would even recommend you buy a used Generation 3 Glock 22 (finger grooves in front of the grip) as they are very durable and reliable. I have shot over 300,000+ rounds through my stock G22s and they keep ticking away.
I am considering getting the sigma 
