Power Player
Bionic Poster
^ I'm not convinced that that outright sq" is the key issue. Hoop shape of the YTPMP is rounder than the G-PP. Much of the YTPMP stringbed area is very usable, whereas with the G-PP you're looking at a smaller usable area (irrespective of whether the hoop is sightly bigger/smaller/more oval etc) and a smaller sweetspot with power dying or it feeling nowhere near as plush outside that mid to lower mid stringbed area. Personally, I don't find it a problem, but the usable stringbed areas are slightly different.
Really interesting, and makes perfect sense. Did you try the S as well or just the Pro?