For the record, SRAM made and or makes two lines of MTB product as far as the actuation ratio goes. Their earlier stuff was all 2:1 Rocket, Grip Shift (original) etc. Their web site lists the actuation ratio for the various shifters. For example, the attack shifters are 2:1 and are available in Grip Shift or trigger
http://www.sram.com/sram/mountain/pr...rigger-shifter
They did this in order to be completely compatible with Shimano equipped bikes and break into the market. My guess is that the rear dérailleur you are using is one of their 2:1 models so it would be no shock at all that it works well with Shimano since it was designed to do so. They still sell some of this stuff but developed their 1:1 ratio for a variety of reasons including brand differentiation. I find the 1:1 products to be far easier to keep in adjustment and use them exclusively in off road racing as well as my recumbent tandem. With the XT I was using, I had to adjust cable tension all the time and the system was highly sensitive to dirt - a rather common aliment off road. With the X.9, I can ride through creeks, rain storms, snow - whatever and the stuff just flat out works well without so much as a minor adjustment. After the first adjustment for cable stretch, I didn't touch it again for 3 complete seasons until I finally bent the rear dérailleur in a race. I still finished and just replaced the dérailleur later. The shifters have still not been touched since I installed them a few years ago. You can do what you want to criticize SRAM but the info on their web site is rather clear and just a few goggle searches will net a ton of info.