Mt XT cassette has performed perfectly all winter through muddy training rides on my mountain bike. It's performing so well I've continued with it into the racing season. Perfect shift every time.
Totally different design than the pinned 9sp cassette that came on my wifes Giant. The stock unit was junk and came apart on the trail, it was a low end Shimano cassette. the CS-M770 uses a one piece body that interfaces with the freehub in one big piece and meets the standards I expect for upper line Shimano gear. A good purchase and a great upgrade.