The 686 is fantastic. The Hogue grips soak up recoil beautifully, even with full-house .357s, and the trigger is excellent...even the double-action is very smooth. 6" is a good range-sized gun - less muzzle flip, more weight, longer sight radius. Not to mention that wheelguns are much simpler to deal with than an autoloader - you can check whether it's loaded much faster, takedown and cleaning is faster, and feed reliability is about as close to 100% as you're going to get (magazines seem to be the biggest problem with most semis).
Not sure what kind of competition per se, but it's a great target gun, and IPSC has a revolver class if you ever want to get into action-type shooting.
Go for it!