Originally Posted by Spyder
Although a lot of knee action should not be discriminated against I personally know it often is.
Depends on what discipline you're in! I don't know a lot about desired movement for dressage horses but I do know that a horse that's considered to be a good dressage mover isn't necessarily a good mover in the hunter world, and I think knee action has a lot to do with it (not positive on that one though). A good hunter should have an efficient long ground covering sweepy stride that doesn't waste energy/length of stride by going "up", you want it to go "out". The purpose of a hack class is to determine the suitability of a good horse out in the hunt field: long efficient stride, quiet and pleasant ride, etc. Whereas (from what I hear) dressage people want more suspension, and I'd have to think a little knee action would be ok.
Question, how common are aluminums in the dressage or eventing world? They're a dime a dozen in the hunter world. The bigger the show, the more common they are.