Hi Dave.
I flew six years with a 7.5 lb pattern plane, with a piped and pumped 91FX in the Advanced Pattern class. A piped and pumped 91FX gives about the same power as YS 110.
Yes, you would get the same with the 1.20 AX, but some people prefer to go with a pipe which generally gives a 15%-20% power increase. So both set ups would turn a 14x10 or 15x10 APC.
Coming back to Pattern flying after a few years in IMAC, I recently converted the plane (a scratch built Desire) to an 8 cell electric set up using an E-flight Power 90 turning an APC 17x10 at 8,300 rpm, which I would say is even better