To answer your more recent question mboy, there is very little difference in weight between SLX and XT for 10-speed.
I am in the fortunate position of having both an SLX-10 (M660) and XT-10 (M771) waiting to go onto a frame and for swap-out from SRAM X7/X9 on a new Scott.
These are the weights according to my digital kitchen scales (in grams, 5g increments in measurement), in the format item: XT / SLX
RH crank inc chainrings, triple: 560 / 605
LH crank: 230 / 235
BB: 100 / 100
Cassette (11/36): 350 / 380
Chain: 275 / 280
Levers & cables (no outers): 300 / 310
Front mech (top swing): 155 / 155
Rear mech (long cage): 245 / 275
Overall difference = 135g (6%). Not much really if XT costs 50% more than SLX.
I don’t have either SLX or XT brakes to compare weight.
The Scott should be with me either next week or early April. The frame, a Karate Monkey, is out of stock until mid April. Neither is going on a bike until then so I can’t give a comparison on which feels better, and in any case when built up the bikes have different purposes and will handle differently anyway so a direct comparison will be difficult.
GaryLake’s suggestion is good, unless the price difference of selling off the SLX shifters and buying XT means that it would be close to the price of getting XT in the first place. Service from Germany (Action Sports) has been great.
Hope you find this useful
EG