like what 2slow2matter said having the .60 version is a good idea in my opinion because once you grow out of your trainer you can take the engine out and put it in another plane. Of course you can do that with the .40 too but the .60 has more power so that it makes it more compatable with larger sized planes. I have the Alfa .40 and i like it but i bought it before they came out with the .60 size..i just wish i could have got it just so i could put it in another plane that needs that size but the .40 did the job and i'm now hooked on rc planes.