I own the Endorphin and have ridden the Norco Sight (though not recently). I would say that the endorphin is more a lateral upgrade. It will be better in some ways ( more composed in rough and steep terrain, more active over rocks, stiffer, better long term durability, etc) but while it is a very good climber and is quite "snappy" and "poppy" compared to other Knolly offerings and many horst link bikes out there, I think there are other bikes that probably are more snappy and responsive. The SC 5010c, Turner Flux Carbon, and Pivot Mach4c come to mind.
Having said that, each of those bikes give up some AM/enduro capability to bikes like the Endorphin, and Transition Scout.