I skied Green River Canyon last year as part of Steep and Deep Camp (guide was David Samuels -- quite good). This week my group from Copper skied Zero G (first 3 turns on belay) and Four Pines with Kent ? (head guide -- an amazing skier). I also had the opportunity to ski with AJ Saunders, who crosses over between the ski school and the guides -- and is a Level 3 examiner.
All of the guides I've run across at JH are incredible. They know backcountry skiing, are careful, knowledgable about avi danger, and teach you the basics of back country safety. I highly recommend them.
I also understand that Bob Peters, a regular poster here, is a BC guide at JH, and he definitely can add first-hand experience!