Join Date: Jun 2010
Location: On my horse's back! Obviously!
I think that if a full cheek works well, then why change it? You can always do it just to see if it works, I've done stuff like that with my horse. In fact, I just switched my horse to a D ring. It might take some getting used to, my horse was used to a stronger bit, so it took him a day or two to "respect" the new big.
If the horse responds well to the bit, and is working correctly (in frame, on the bit, etc) in a show, the judges shouldn't really care whether or not it's a full cheek or D-ring.