Al Stein

A data point to throw into the equasion: A guy in our club has one (i.e. an electric Aspire) that wouldn't climb on the stock power package and broke the prop.

He replaced the folder with an off-the-shelf glow engine prop and it climbs out just fine now. I haven't studied what magic people do to design a prop for electrics, but whatever the magic is, it may be a mixed blessing.

FHHuber

The glow type prop has less blade area (usually) at the same dia and pitch. This reduced engine load, and could simply mean that the guy who had problems needed one more cell in his battery pack to properly turn the propellor. I found that the Master Airscrew 3:1 geared motor with folding prop setup really needed 7 cells. (even though the instructons say 6 or 7...)

Just another data bit in figuring out the electric conversion: Unless the kit's instructons show how to do the conversion, the wings normally will need reinforcement. Having the power on the plane tends to make you do more aerobatics, and pull more G's. That combined with the added weight of the battery can lead to overstressing the wings. (Compare Gentle Lady to Electra, both by Goldberg. Same planforms, one's electric the other pure sailplane, major structure change to wings.)

You can avoid changing the structure... but if you do, be aware that a tight loop is a bad idea.