I've attended the same classes as ARH.  Actually, he's my partner in all the drills and it helps a lot having a buddy point out things (i.e. mistakes and room for improvement) during your drills.

I always take a spare AR and pistol just in case.  If something happens, I can just grab my backup and stay in the game.  Do you absolutely NEED a backup?  No.  If you don't have a backup rifle, don't let that stop you from taking a class.

I've never had a single problem with any weapon in any of these classes.  Maybe I'm just lucky, but I do things to improve my chances of not having a failure.  I keep my stuff clean.  During the breaks I check my gear and clean things when they need it.  I only use good quality ammo and magazines.  The biggest issue I've seen in these classes has been related to magazine problems.  I test my stuff before the class to make sure it is all functional.  

I highly recommend some form of training if you want to be a serious shooter.  Contact Mike Bennedict of Talon Tactical.  He posts here as mikebenedict, so IM him.  He can setup a class at the Pickens County range with Claude Werner (aka The Headhunter).  Mike and Claude are EXCEPTIONAL shooters.  Your skills WILL improve greatly.  Trust me, this is money well spent.

Good advice on South River.  Also, for basic pistol skills, check with Mike Benedict (mikebenedict on this board; IM him).  He can probably setup something at Pickens County gun club with Claude W. (aka Headhunter).  They'll get your pistol skills quickly up to par.