Well when I look at MTB HYDRAULIC BRAKES: LEVER, CALIPER & DISK, I immediately think there is so little to them, that they are far too expensive for so few and little parts.
The prices of XT, XTR & Saint are so expensive, I wouldn't masquerade myself that I could afford Shimano's finest (i.e. I can't afford, even if I did like the name of the world's largest groupset manufacturer, and following implications).
But even at DEORE level, also with online discounts, they're are not even sold in pairs! Or in many instances not even with disks/rotors either! And I guess sizes larger then 16, such as 18 or 20, don't come with offset caliper adaptors to reach your IS/Post Mounts on your frame/fork!
And don't forget that shimano brake calliper seals are not replaceable.When they leak consistently you throw them in the bin.
To be fair MTB calipers are very intricate, if the caliper piston(s) did seize, or the caliper piston seals ripped through age/use I'd be very very surprised if you could dismantle the calipers to replace the caliper piston seals, that is if you could even buy the caliper piston seals separately.
But I bet you rich c*nts with Hope, Hayes or Avid Hydraulic Brakes, will tell me "You can get the caliper piston seals separately", well good luck in undoing your old caliper, without smashing it to a thousand pieces, if not have fun NOT knackering the new caliper piston seals whilst trying to fit them.
Giant Trance x1 ~ 2008