For those that have never handled/seen one and are perhaps contemplating a set, they're a league apart from the stock item. The one piece design means there's no annoying split between the two halves which always managed to become slack and slightly misaligned on mine no matter how much I packed out the tang or tightened the screws and your middle finger no longer rubs on the trigger weight adjustment screw either. The palm shelf setting works by two Allen screws adjusting the height with a separate lockscrew to keep things fixed in place - I can't see it allowing any sliding or wobbling in a hurry.
More subjectively, it fits my hand much, much better than the old lumps of timber although that's hardly a surprise as they were just stippled rather than shaped to suit. I can't emphasis the night and day difference between them enough. The rake angle is different and the pistol points better - the Izzy's inherent nose heaviness seems less prominent and more easily compensated for. I may be lucky in that Rink's off the peg dimensions fit me well but it's comfortable, grippy and just feels "right."
There's no denying the price is steep and the money could be put towards a more capable PCP but they're quality items and, as brent375hh said, I couldn't be happier. It's like shooting a whole different, and better, gun.