I've had experience with the Hotrail, the quarter pounder and the red lace sensor single coils along with stock ones of course (Jag, Jazzy and MM), all used with solid distortion out of the upgrade's i'd put the hotrail at the bottom of the pile. It is higher output and pulls off tricks like pinch harmonics and smooth controlled feedback better than the other two but it is less refined. The other two seem to have more clarity and the notes really stand out.
I suppose its a tough decision picking pups, its taken me years to find the right one(s). Everyones taste is different, mad-mike for instance likes his 'cool rails'.
