I agree TBs are an awesome breed. Anglo Arabs (Thoroughbred x Arabian) are usually very athletic, intelligent horses. If you're looking to do anything in the English world (particularly eventing) Anglo Arabs are a good way to go.
I have an arabian x rocky mountain cross that has jumped up to 4 ft and is starting to learn dressage. I LOVE LOVE LOVE my arabs and arab crosses. I can't connect to any stock breeds like I can with arabs.. There is just something about them.
My Arab x Welsh pony is a great low level jumper and dressage pony. I've jumped courses on her up to 70cm, single jumps up to 80cm. She could go miles higher, (but I can't!) her form is good and she enjoys jumping. Her dressage is nice and soft, I think I could take her up a few levels if I was a better rider. We haven't had any problems in the past wth collection or hind quarter power. Our biggest dressage problems are walking out more and leg yields, our biggest jumping problem is the random flying lead changes she likes to chuck in when she's excited. (No, I can't figure out how to get them on cue)
However, she's is 3/4 arab and all of the Arab bits are from colonial lines (endurance/racing, not showing) so she naturally has a bit of strength there. And her mother (1/2 Arab, 1/2 Welsh) was an A level show hunter so that's probably where the jumping came from.
He's not registered unfortunately and the girl that's selling her doesn't know his site or dam, just going off what the lady she bought him from years ago said. But he definitely has a very thoroughbred-ish look to him. Not real tall 15.2, but his conformation and hindquarters are that of a thoroughbred. I'm going to try and have him registered when I buy him.