In my opinion, they don't.

I have RealFlight G3.5 and one of my planes is a trainer. The trainer in RealFlight handles a lot like my model in flight but takeoff and landing is less realistic.

Almost any model in RealFlight will make a perfectly straight take off roll and will climb out if you slam full throttle and give a tiny bit of up elevator after picking up some speed. Real models often do not do that.

If your 'second plane' will be a 40 size, the price of a 40 size trainer ARF airframe is really cheap for learning the basics and getting soloed. Wear out the trainer, or fly it until you are bored, then move the engine and electronics to the other plane.

One example of 80 dollar ARF trainer
http://www3.omnimodels.com/cgi-bin/w...I=TOWA1110&P=0

The model airplane hobby is not cheap. It gets even more expensive if you try to jump past certain steps in the learning curve and end up destroying your stuff.