What ball has the sharpest "back-end" with all things equal. Lay-out, revolutions, lane surface, speed etc.? My chart shows: Global The Nuts Pearl, Columbia Ransom Demand, Encounter, Elite Platinum, Hammer No Mercy and No Mercy Beat'n, Taboo Electric Silver/Blue, Roto Grip Epic Odyssey. All are rated at 17.5 Back-end.