I have done numerous tests within a manufacturer(if they have both a 2x and 3x available) to see which is the lighter setup. The most recent was 10 speed SRAM. The thread was either on here or on Slowtwitch. I list the parts for each, the weights(directly from the website) and the results. If the compact 2x has to go 32t or more to match the range, the 3x is the lighter setup. Every time this has been the outcome. This was comparing a 2x vs 3x with the same number of cogs in the back. Take 2 or 3 cogs from the cassette and the 3x becomes even lighter. In fact, the only weight advantage the SRAM 1x with the WiFli held over the 3x was no FD/shifter. Add either one of those and there was no weight advantage. The reasons? Big pie plate cogs in the back are heavier than the small 3rd ring/hardware. You also have to run a big RD in back with 2x. Not so with 3x. The FD weights are not much different. That is what I have found no matter if you are running SRAM, Campy or Shimano.