As for the xo's just because they come on a dh bike does not mean they are meant for it, I would never ride XO'S on a dh bike , sure they may work depending on how much you weigh , I have just seen way too many elixr brakes with issues to trust in them.. Saints > XO's - IMO
hope they last long enough... too bad the cs' break on trek's. they ride great! oh yeah.. still didn't get mine back from warranty. the shop in italy told my dad that they can't change the cs' because it's passed the 3 year mark on the frame ) dumba*s shop guy don't know that tha warranty on the cs' is 5 years ). hope to get the problem solved soon...