I run a short (mid cage) XT with triple front & 11-34 cassete with no problems. The mid is lower profile than long so the rocks tend to hit it less. Some guys will run a road der on a 1x9 setup.
Shimanos "short" or "mid" is a bit longer than the sram "mid" cage. You can actually use every gear combo with it, not that you should, but it's good to know you wont rip the RD off on a missed shift. The SRAM mid cage is not quite long enough to use every gear combo. On the big ring, I wouldn't use 2 or 3 largest cogs under and circumstances.
The benefits of the shorter cage RD's are quite nice, however. I'm using a mid cage x.0 on a triple front, 11-32 rear and it's lighter, provides better clearance, doesnt flap around even close to as much as a long cage and it shifts alot faster, more like a road mech.