The sad truth of it is that a four stroke is an investment risk in a trainer. There's a very good chance you'll plant it and a two stroke is less of a loss if it's a hard plant.

A for stroke is a worse choice for a second plane, because you're even more likely to crash your second plane. That's when you start to think you're good and try the more radical maneuvers.

Put one in your third plane.

And when did the "industry" start calling glow fuel "nitro". I see that frequently anymore. That's like calling everyone on a baseball team "pitchers". There's zero to 15% or so in avaition glow fuel, so it must have leaked in from the R/C car segment. It's methyl alcohol, castor oil and then a bit of nitromethane as an afterthought. In a trainer you might as well use the fuel that has none. More nitromethane in a trainer just makes it harder to fly level at full throttle. Speed = climb with flat bottom wings.