Trooper is a 14.2 or 3 horse, 1/4 Appy & 3/4 Arabian. I weight 175-180, and if I bother him, he hides it well. Mia is taller, but still only 900 lbs. I ride her 4-5 times/week. If you're too big, I need to get out of horses and buy another truck...
I don't jump, so I don't know how that affects things. On the flats, you'll be fine.