I understand your point of reasoning, and like I said, I have talked to several that have used the 120 and are happy as clams with it. And please by no means take what I say as gospil. I have not used the 120 on this Plane, so I am no expert on it. I just wanted to let you know that the 100 does produce alot of giddyupgo for this Plane, and I have read post from others who are quite satisfied with the 91 Magnum and Saito also. I just wanted to make an opinionated reply to the subject of your post since I do have this particular Plane being discussed. The 120 Magnum should be a fine choice , as long as you don't mind the little bit of extra weight, and from all that I have read, plus learned from my own, it should track straight as a string no matter which engine you go with. Its a great airplane, and I hope you enjoy it as much as I enjoy mine. The quality is superb!