For DH you may see a few advantges but there are also some major disadvantges. Higher center of gravity making it harder to initiate turns, this is where time is lost or made on many courses. Less tire choice at the moment, and probably wouldn't change for a while. wheels are weaker. and the biggest issue is the mere lack of travel. for a lot of courses 7" is not enough you can get by but it beats you up. 29ers may work for XC but DH racing is a whole different ball game, it's a 2 to 5 minute pure sprint. I personally don't think we're going to see them on the WC circuit anytime soon.