FMS is very effective as a training tool depending on the accuracy of the model and the type of airplane you want to fly.

You can learn orientation, landing approach, how to handle wind and gusts and differences between slow models and fast models, aileron trainers, R/E/T, A/E/T and 4 channel airplanes.

Others tell me that as you move more toward 3D flying or acrobatics that the other sims are more accurate and better at training the thumbs.

-- ggunners