I've set up my ML2 with a 2x9 drivetrain with 24/36 front rings for this season, but I'm having issues with my XT (770 low mount) front der. as it won't shift smoothly. The chain falls off, slow shifting etc.

So I'm considering the new SLX two ring specific front derailleur (FD-M667), but I'd like to hear if anyone here has given it a shot? Should I go for the low mount or the high mount?