Not a thorough comparison, but it is real world with stuff I had around. Calibrated for the cap used to hold them up in the pics.
XTR M972 long cage new. Also takes shorter cable & housing than non-shadow, similar to SRAM. 5 grams of cable and housing less, based on a side by side installation/replacement of the M952 below on the same bike with the same old cables and housing cut to fit.
XTR M971 long cage new.
XTR M952 long cage used, with rubber bumper. Bumper weight 2 grams.
'07 Sram XO long cage used.


XTR M971 long cage new.

XTR M952 long cage used, with rubber bumper. Bumper weight 2 grams.

'07 Sram XO long cage used.