I've flown:

H9 Cap 232 25% ARF
H9 Edge 540 25% ARF
Sig Cap 231EX 25% ARF

Have built the Lanier Laser 25% Kit and the MW Extra 300S 27%.
The Laser flew for 3 seconds and then my engine flamed out and I crashed it. Haven't flown the MW Extra yet. Maybe 2 or 3 more weeks and I'll be done building it.

For 25% planes-- use a glow engine. They just don't have a big enough airframe to carry the weight of a gas engine. The glow engines that are big enough to fly these size planes, with any authority, are going to run you into the poorhouse with the cost of fuel. A Moki 1.80 or a 2.10 will suck down a 20 or 24 ounce tank pretty quick. Thats fine for IMAC-- you only need to fly for about 3 or 4 minutes anyways. The problem is when you want to PRACTICE. If you ever want to get good at aerobatics--your going to have to fly----A LOT. The glow fuel expense adds up very quickly. Of course you could always brew your own glow fuel--but who wants a 55gallon drum of Methanol in their garage or basement??? And you'll probably use some nitro-- just to make it easy to tune-I certainly don't want nitromethane in my garage. So your pretty much stuck with buying glow fuel at $13-$15 a gallon.

For a bigger plane; such as the 27% Extra that I'm about to finish; you can and should run a gas engine. They have enough square inches of wing area to support the gas engine and ignition system. Gas engines are MUCH cheaper to operate. Fuel is basically $2.00 per gallon after you figure the cost of the fuel and the oil. Gas engines use less fuel per minute than a glow engine. That equates to a smaller tank in the plane- which saves weight. Gas engines have pumper carbs. -- you can put your tank on the CG and not worry about pulling fuel to the carb. They can suck fuel a long distance and still run fine.

If you can afford it-- get at least a 27% or a 30% plane to start with. Get a gas engine. Bigger planes are more stable and the gas engines are more reliable.

My $.02