I really can't believe some of the people who post on this topic. If you don't think kids should compete in contact sports then ok I get it, I don't agree with you but at least you're consistent. I would expect you to be even more opposed to tackle footbal, hockey..... check the injury stats
The amateur MMA that kids compete in in California does not allow strikes above the collarbone so from a striking perspective it's more conservative than many common TMA sparring/kumite matches & has reduced concussion risk for kids. The rest of the rules mirror NAGA which is well established and accepted.
I have three kids who love to compete in BJJ/Submission Grappling & Amateur MMA. I don't "push" them and never have, they are in incredible physical shape and none of them has ever started a fight. Anyone who thinks they aren't learning useful skills doesn't know what they are talking about. Check it out
8yr old boy beating a national level judo playerhttp://www.youtube.com/watch?v=85vMsJtxk4w
9yr old girl after 6 mo's of training, she's much better nowhttp://www.youtube.com/watch?v=PY4np2VZ5Mo
12yr old boyhttp://www.youtube.com/watch?v=IeIQgIbvx8A
Every match my kids engage in starts and ends with respect & a hug or pat on the back, win or lose.