joh3927805 wrote a review of Shimano Saint RD-M810 Rear Derailleur on October 31, 2010
I was getting too much chain bounce on downhills on my AM bike (Trek Remedy). This replaced my stock XT long cage. The long cage Saint derailleur has a shorter arm than the XT long cage, maybe a little longer than an XT med cage.
The super stiff spring means less chain bounce; and this derailleur really tucks itself out of the way of rocks and logs.