I am running the M485(previous gen) and have no problems with them. Not the greatest stopping power, but a solid brakeset. Actually, getting ready to try out a 180 mm rotor in the front to see if that gives me the extra power I have needed a few times. Good modulation and easy to service.
I have been using the M485 for the past 3 months. It's my first hydraulic disc brakes set. So far no problem for me. Adequate braking power for me though I mostly do road and elementary XC riding. Nothing too difficult.