I had one of the GB .90-1.20 sized arfs and it flew great. I started with a 1.20 4S, but the wing loading was not to my liking. I mounted two mini high torque servos in the tail to couner the heavy 4S engine. It would climb out of sight and flew okay. They did not have the OS 1.20AX out then, so I opted for a .91 FX and it flew more on the wing, like the kind of flying you are looking for. Around this time, Tower dropped the price of their 30% Ultimate to the basement and I bought one, since I already had an unemployed 3W75 collecting dust in the hangar. Once I completed the 30%, the little Ultimate became a hangar king, so I traded it, ready to fly for a 9Z transmitter. It is still around somewhere.

A very good friend has one with a Saito 1.50 on it and it goes crazy. The 1.50 weighs about the same as a 1.20, but still, the landing gear in the arf isn't the strongest. If you go this big, you may want to beef the gear up. Also, put some servos in the rear, rather than adding weight, performance advantage of servos mounted close to the control surface, reduces the chances of flutter and blowing the surfaces during high speed aerobatics.

I really think the 1.20 AX would now be the engine of choice for this plane, expecially if you are thinking of any 3D at all. Ultimates can be addicting. Whenever I take my 30% to the field, everyone wants a shot at it, and they all giggle when they start the snaps and flat spins these planes accel at.

Good Luck and happy holidays,
Mike Boyd