Just browsing through catalogs and such ive noticed that alot of race hardtails use the shimano x61 version of the xt and xtr derailleurs instead of the intended x60 series. Usually the clamps end up coming between the waterbottle mounts as the x61 uses a higher clamp. Is there any advantage to this setup? Other then a 961 derailleur being quite a bit cheaper then the 960 model?