I have the YS 1.10 in my Venus and a friend has an OS 1.20 AX in his. Both fly the plane well. The 1.10 has incredible power for its size. You will not get fuel savings with the 1.10. It uses more fuel and the fuel it likes is more expensive. Make sure you have the muffler pieces and the muffler securely attached. I know of a few guys who lost the end of the muffler in flight. The OS is a smoother running engine as far as vibration goes. This is my first YS and will likely be my last. I like it a lot, but it is expensive to run if you do a lot of flying.