What Steve said. Even with, say a .91 4 stroke replacing a .61 2 stroke, the fuel consumption is less. Been there, done that.

Price is a non-issue, essentially. If you are spending several hundred dollars on a scale, or near scale (built up or ARF), what's an extra 40 to 50 percent cost on a motor that will burn less fuel and probably last longer due to less RPM turned?

Of course the same argument could be extended to radios, servos, wheels/tires, ad infinitum. PCM or FM? Computer or standard? High torque, high speed, or standard $15 servos?

What do you want to spend? What's your style? I like to spend more whenever possible to buy a 4 stroke regardless of whether it's a scale or aerobatic plane. It's my style, and my choice based on years of messing with both types of motor.

Just starting out? Get a 2 stroke since it wont hurt quite so bad if you bury it in the dirt.