I helped a friend install a group recently and weighed everything. The crankset is pretty heavy. I don't know the actuals of a 6800 group but here are the weights for most of 22:
shifters 312 (156f/157r)
front derailleur 87
rear derailleur 166
bottom bracket 106
chain 251 (full length)
He's using a Red cassette but I think a PG-1170 is around 240g.
Since you're using 9000 shifters already, the difference is not going to be large at all.
I feel stupid now that, I didn't weight my parts. I was so excited to have the parts so I put them on the bikes asap.
Thanks for the numbers. I compared them with numbers I found at BikeRadar.
Here is a table for my equipment vs. Force 22Equipment | Force22 | My Bike | Difference
Shifters | 312 | 364 | -52
Front Derailleur | 87 | 89 | -2
Rear Derailleur | 166 | 195 | -31
Crankset | 717 | 765 | -48
Brakes | 286 | 335 | -51
Cassette | 231 | 212 | +19
Chain | 251 | 239 | +12
Total will be 153 grams.
I don't know BB weight in sram, but new Shimano BB is 77grams. So I believe there will be 30grams of difference there, and final will be 120 grams.
Switching to DoubleTap shifters is a huge gamble for me now, and I think, it is not a good idea to play it just for 100 something grams.