Agree with corporal.i have had more issues with soundness in stock breeds than arabs. My mare is barely 15hh and 800# and she packed her previous owner(230# man), a 40# stock saddle plus rifle and full saddle bags through the rockies hunting. Her legs may look slender, but she is solid, and sound, sound, sound.
I have worked with many horses that were used very hard when young, then discarded when they get older. Most of the stock breeds seemed to end up with shoulder problems, hock problems or navicular. The arabs just turned unmanageable from either being spoiled or mistreated, but almost always remained sound.
I LOVE an arab cross, my mare is in foal for an anglo arab next year