Chip, every engine you mentioned is more powerful than the OS 40LA. I can't think of any other 40 class engine that is not more powerful than the 40LA. The 40 LA is not my choice for sport flying, aerobatics, 3D, etc. But for a trainer, it is a very good choice. One of the good things about it is the limited power level it produces. Good for learning how to fly a plane. On mine, the "training cruise" speed is at reduced throttle. I have worked with a flyer with his own Avistar w/40LA, and coming back on the throttle is an important part of the flight training. Another plus is the user friendly performance, also the miserly fuel consumption. All good features for a training set up.

Mostly, when I see people advising newbies to get a 46 powerhouse for their trainer, the rationale is that the more powerful engine will be suitable for that "next" plane, after the trainer. In this case, Hitec Man is looking for a trainer set up, specifically. I can identify with that!

There are lots of possibilities that can work.