I have to agree with everyone else here. Learning is one thing, but allowing them to actually compete at that young age is not the right road. Kids can get hurt at that age very easily. They need to have the competitive cutoff around mabye 12-15yrs old. Learning it, though, is a great thing IMO.
Nobody understands how individual sports teach you to be driven and disciplined. It is not like team sports like football, basketball, baseball, etc....Its just a different breed all together. I dont mean to bash team sports, but anyone who has done individual sports TRULY understands what i mean. I was a wrestler, and anyone else on here who was/is knows FIRST HAND what i mean. It will be in your blood for life. It becomes a part of you. It is one on one and nobody can be blamed but yourself. You are in the spotlight with one other person. You cant rely on anyone else come "game day". It teaches you to be mentally tough. It teaches discipline in training, cardio, eating, and how you live. I believe it can be a great thing.....if harnessed correctly.
Now if your kid is learning to fight and going to school and thinks its ok to pick on people, thats a different story.....