RE: Foam vs. Gasser
Yes, there is definitely a difference. The biggest I can think of is mass and inertia of the airframe. The 40% is not going to be as "twitchy" as a foamy airplane....and a bit slower to respond to stick movements simply because it's a much larger plane. It also won't get knocked around in the air as much as a foamy.
Gas engines also have more of a throttle lag than electrics. With an electric motor....100% of the torque is available from 0 RPM up, and blipping the throttle results in instantaneous response from the motor. With any glow/gas plane, there will be a little bit of a lag from when the carb opens up to when the engine actually spools the prop up to make the airplane respond.
Others who understand aerodynamics better than I can probably share more differences.