That's a very good point about not buying an engine for every plane, and I fully agree with you. However, with this being only my second, I'll probably buy an engine for it, so I can have two planes to take to the field. From there on out though, I seriously doubt I'll be buying an engine for every plane. Like you said, they're too easy to swap out.

So let's say that I decided to go 4-stroke (not that I have, I'm still leaning toward the OS .55)... I could go on the cheap (kinda) with a Magnum 70RFS at $180 or go with the higher-end Saito 72AAC at $225. The big difference that I can see is the weight. The Magnum is quite a bit heavier at 21.2 oz than the Saito at 16.6 oz, which would seem significant to me for this size plane, but I'm just a newbie. Is the 4.6 oz weight savings worth the extra $45?