XT shadow mech on mine and it is perfect. As is the STX on my old bike and 105 on the road bike. Sure it's lacking 1 barrel adjuster compared to older MTB setups, but the one on the shifter has more than enough range.
All were set up by following the instructions on the Park Tools website.
Only problem I've had is the front mech getting clagged with snow mid-ride, but after letting it defrost and then hoovering out the dried mud it worked perfectly again.