I've been happy enough with 1st generation NX on two bikes and M7000 another, no opinion on XT, it's probably lovely. The cassette is definitely lighter for having a spider, I've heard the shifter feels better. The tandem MTB guys (I'm sort of shopping for one) prefer the "full pin" or even better the $-Dome SRAM cassettes for strength.
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Genesis 49:16-17