GW speaks the truth IMO.
I've not ever pushed a shock for singlepivot, but on my HL 5spot it made the world of difference, holding up the mid-stroke as GW describes. Its stopped the bike feeling like it was a dog dragging its arse along the ground it general.
Specific things I noticed after having it done were - better ground tracking, more controlled yet still compliant yielding of shock stroke, much improved control of rear end wallow on G-outs and heavy, sustained compressions like berms and a virtually undetectable platform action, unlike the orginal pro-pedal.
I pushed my first shock in 2005 and I've had three or four since then. I have had every one pushed as a matter of course. The latest was a 2008/9 RP23 - Apparently with damping so improved it wouldn't really benefit from a PUSH, but by god it has.