RE: what size engine should i use?
I would love to see people buy one of the better engines once in awhile instead of just the cheap ones for them to learn the differences. People only want to see RPM comparisons which mean almost nothing in a true power and torque comparison. In any case, an engine that weighs close to a pound less than anything else in class, even if using RPM as a power comparison, delivers the equivilant of more power through lighter aircraft weights.
In this case there's a lot more difference than that. Same as there would be with an MVVS 58 or a 3w 55. People leave a lot on the table when all they do is shop price.