By "don't know how to use a camera" you mean they try to use a 7D at ISO 6400? Because that certainly is not knowing how to use a 7D.
Correct about the 6400. Not as good as cameras costing twice as much or four times as much.
But then thats not the budget the OP has. For Sports use. Within the OP's budget. 7D=best.
Most 7D moans originate from folk wanting better jpegs than they got from their 50D's. And folk who thought they could shoot sports or nature, but when given a decent AF system with tweakability, wigged out. And folk who thought spending more automatically meant better pictures.
I know the whole noise thing trickles down, in that if its well controlled at 6400 it's going to be far less at the everyday ISO's.
Apart from not really wanting to push the 7D beyond 3200, I can't actually think of an occasion when I had to push it beyond 1600. I think this might be the old film user in me where less ISO is more. Maybe because of my video work I'm just used to adding light, which I know isn''t practical or desirable for many.