I had the same deliema with mine when i was building it.
Decided on the Thunder Tiger .46 Pro. Put this engine in it...
It will Haul a Deb around like there is no tomorrow. I turn a 11x5 on it and it has all the power
it needs to do just about anything you want to do with a trainer. Mild aerobatics are no problem.
Even some not so mild, if you dare with the rubberband wing hold downs.
It is a easy engine to tune and set up, reliable starting. pleanty of power.
I have an Evolution .46 to try on another plane too, but i cant comment on it yet
as i havent even moved it out of the box, accept for the occasional fondle...
Jeff