Honestly, let your horse tell you what he wants to do. I know that sounds corny. But my mare is Arab/QH and is GREAT at reining. She can track a cow like a mo fo (only worked a flag once for fun.) Is phenomenal at gaming. Can do english or western pleasure, even jump. You know what she's bred for? Arab side is english/park horses. QH side is Impressive...halter and race horses. Not one single reiner or cutter, but man she's got the talent!!! Breeding doesn't always mean everything!! As for your colt. Take your time and don't commit him to one discipline in your mind just yet, he could do anything!! I'm not real big on confirmation, but I would say he seems to be slightly camped under in the back. (I could def be wrong.) But, the point of hip to point of butt has a real nice slope, supposedly this means a longer, more forward reaching stride, I find it true. Also, he has a very nice deep V in his chest which will make his turn arounds a lot nicer and much easier for him. That's my advice, wish I was more help!