SRAM XO long or medium cage for 5.5?

I've had two long cage XOs with the 5.5 and no problems other than breaking a tooth off the pulley. But if you run only two chain rings and bashguard there's no real reason to use the long cage. Medium would be fine and more clearance. But if your running say a 11-34 with triples then you should run a long cage if your not carefull with your gears. Otherwise you can't really run say granny in the 11 and also run 34 in the big ring. You can get away with it on a hardtail (i have a short cage xtr and triple its ok but not pretty in the extreme ratios) as the chain length can be setup just right but with the the extra links for a dually your pushing it. I like the aluminium cage too, its strong and have never bent one.

I run a medium

with XTR cranks and a 11-32 cassette. No problems.

I run triple, compact cranks, 12-34 cassette and long cage

I run triples and an 11-32 out back with a carbon medium cage with no problems at both extremes. just have to be careful that the chain length isn' t to short or long.