That Ninja Marlon P wrote a review of Shimano XT Shadow Plus RD-M786 Rear Derailleur on February 19, 2014
Familiarity: I've put it through the wringer
Bought the medium cage silver when I got rid of my big ring and went to a 2x10 setup. It matched up fine since I have XT everything else as far as the drivetrain is concerned. Easy to set up as well, just had to find the right manual online though.