Fine if you want to spend that, but i'll spend less on the best there is.
By what measure? XTR cassettes are heavier and a narrow range and don't last as long because of the ti sprockets.
Having used both, there is absolutely no comparison in terms of performance, Shimano is better and it stays working.
I have also used both, extensively (well XX cassettes anyway, not much first hand experience of XX1 yet but tech is the same), and despite your slightly blinkered view at the end of the day it's a personal choice. Both XTR and XX/XX1 are excellent, there are subtle performance and functionality differences, but conveying your ill informed opinion as fact is a little daft.
Plus, you can save £100 by not buying the XTR cassette with no loss in performance.
You mean £70?
So, for the price of an xx1 cassette, you can have an XTR rear mech and shifter and chain, XT cassette and a Works components ring.
You can have a basic Trek hardtail too. What's your point caller?