I'm running 1 x 10 with the following:
- 34t ring mounted in the middle of SLX cranks
- 11 - 34t cassette
- SG XT Mech
The chainline appears spot on i.e. ring lines up with the middle of the cassette. However, when in the lowest gear (34-34) the cage of the mech (not body) is being pulled too far over by the chain. The consequence of this is that if you back pedal, the chain derails and drops a couple of sprockets.
The mech is aligned properly and the hanger isn't bent. I've played with the B-tension to no avail. Is the chain too short? It's not overtly stretched in 34-34 and is, what I consider, a satisfactory tension in 34-11.