Have an 07 stumpjumper and not overly impressed with the LX shifters that come with the bike. If i upgrade to the M970 shifters and XTR front derailer will i see much improvement. LBS told me not to go to the SRAM shifters as i would have to change to much on the bike. They also said that i would probably not see much difference in the LX to XTR change in shifters or derailer. Any information here would be greatly appreciated.