Hubs will be fine with 11spd Shimano. I've just got myself a cheap XTR 10 spd full kit.... Hey ho.
If you need 40/42 teeth on the back then get your sparrow legs on an ebike.
The cassette seems expensive. XTR 11 speed was cheaper than XTR 10 speed.
Njee, you'll notice I said 'was'. M980 cassettes were £200 when M9000 lauched. And XT cassettes have gone by about 60% in price
cassette is quite heavy at 411g