Height isn't a huge factor. It depends on the heart of the horse and the SPEED that they can complete the pattern.
Sherry Cervi's world-champion mare Stingray is only 14.2 hands. And Sherry is over 6 feet tall! But they obviously work well together and run a very, very nice pattern. And Stingray can boogie! And she gives it her all every run.
When buying a prospect, I'd look more at what her breeding is and what her parents/grandparents have accomplished in the barrel racing world.
Of course, you never know how a barrel prospect is going to do until years and years down the road, but that's the whole point of buying your own prospect vs. a trained finished horse!
∞•*˚ Βгįťţαňγ ˚*•∞
It is not enough to know how to ride; one must know how to fall.