Fred Franzelbarwrote a review of Shimano XT Shadow Plus RD-M786 Rear Derailleur on September 27, 2013
Familiarity: I've put it through the wringer
This replaced the same model in sgs or long cage. The medium cage works much better with 2X10 for many reasons here are a few. Shorter chain [ 6 links lighter ] and less chain movement up and down. Lighter and less obtrusive than long cage. Quicker shifts even with the clutch activated. Looks better because it is more compact.