I use Realflight in a different way. I will input a plane from the plans, install the expected engine power and fly. I then make changes to the control surfaces, throws, incidence, to arrive at the performance I want in the real plane. I have entered some from plans that I found dissapointing and then did not build. I have converted some freeflight oldtimers and was able to change them so that they behaved well as an R/C. I always try out my scratch built designs before wasting the balsa.
The simulator has saved me considerable money and time.
Hey its a great diversion during the long cold winters in Michigan.