I use a Predator Z2 and have a Mcdermott with standard shaft also, using the z2 its much easier to draw or follow it requires less effort. If using left or right english requires less deflection in aiming the cue why wouldn't it also cause more draw or follow than a standard shaft. The LD shafts will generate more spin with less effort whether its top, draw, left or right, I think the key here is LESS EFFORT.
I also like the feel of the Z2's smaller shaft diameter.
Easier to aim a thin shaft than a thick one for me as well.