Before I used Sram XX1 on my bike but this year I go a bit cheaper with Sram X1 that came with my new bike.
Cassette is the thing that gains the most weight:
Trigger with wire:
KMC X10 chain:
And the rear derailleur:
The derailleur isn’t so big difference in weight between XX1, X01 and X1. Check my earlier post with XX1 and X01: Sram X01
And to complete it a really tuned Sram XX1 derailleur by two German guys. Found it on Eliflaps blog
Mounted on a Specialized Stumpjumper ht:
jonas wwBlog 