Here are my actual weights going from Bronson stock RAM setup to XX1. These are the actual weights on the scale, including bottom bracket. In general, I found SRAM posted weights to be slightly lower than actual (but not always) and Shimano was right on (within 2 grams on average).
Front Dérailleur XX1 0
Rear Dérailleur XX1 266
Shifters XX1 110
Crankset XX1 32t 680
Cassette XX1 10-42 244
Chain XX1 260
Total 1560
Front Dérailleur Shimano M611 or 610 (Deore) 148
Rear Dérailleur Shimano SLX M675 Shadow+ 310
Shifters Shimano SLX M670 300
Crankset Shimano (Deore) 24/32/42 (950) 980
Cassette Shimano HG 81, 11-36 (SLX) 10spd 345
Chain Shimano HG 75 10spd 268
Total 2351
I saved 1.75lbs. I did not weigh the cassette adaptor. I did XX1 at the same time as putting on LBS 30/35mm hookless rims and it's like I'm riding a brand new bike. Amazing, amazing difference. So far, i don't miss the 3x (granny gear) on the front at all.