Based on what flyboy said, I would have to say he is correct. Besides, why would you want to spend the extra dough on a 4 stroke for a basic trainer? Your cash, but I CAN tell you that the eagle 2, (as far as I know as I built one from scratch but may not still be the case) uses plywood pieces fused together as an engine mount that you epoxy to what basically boils down to pieces of stick (spar like material) onto the sides of a VERY thin plywood side fuse. Therefore, I thought about vibration becoming and issue and ensure that is very secure before every flight. Not to mention, I have been seen dropping some CA in and around the area every so often. So I would venture to say that if the 4 strokes cause more vibration than a 2 stroke (Ima newb so don't know) then that would be the reason.

Hope that helps buddy.

S