APHA isn't as bad as Quarter horse with monster horses... I just got my English Equitation ROM on my 15 hand gelding. :) With that being said, sometimes we are hidden behind 16-handers, hehe.
However, don't make him go that slow yet, or all you'll be doing is teaching him to disengage his hind end and travel like 80% of other WP horses. The 'great' wp horses aren't any better then the others by skill.. they're just TRAINED better. He needs to know how to go forward in order to collect; so bring his head up a little bit and allow him to do so. If you leave his head where it is, you'll just be running him into the ground. Like many good trainers I have known say: the main mistake people make when training a western pleasure horse is making him go too slow too soon. He'll be dragging himself along by the forehand in no time.
Other then that, he's a very pretty, slow-legged mover, although I didn't get to see him lope and that is 'the money gait', lol. I really like him a lot, and good luck with him ;)