Sorry to necropost in such an old thread, but I just wanted to chime in on using the RealAir FS9 .air file with the Carenado.
I'm currently training in a C172M, and I absolutely love the Carenado 172N and use it daily for training between my weekly lesson flights. However, I found the default flight performance was very different from the real aircraft. One example is simply found in flying the pattern. Not only does ground speed seem to be higher on descent when using the original configuration, but the descent rate with flaps at 10 and 20 is much steeper than on the real aircraft. after just a few flights I had developed the habit of adding a little power as I turned base. Naturally, during my next real-world lesson, flying the pattern for my first 2 of 4 touch and go landings my muscle memory kicked in and I added the power on base, and as a result my first two approaches were much too high.
As many have suggested, I tried using the RealAir file with the Carenado, and I couldn't be more pleased with the result. This aircraft now performs almost exactly like the 172 I'm training in.
I also own the A2A Accusim 172R Trainer. I'm going to do some more flights and maneuvers with the RealAir FDE file, then try the A2A file, performing the same maneuvers. I'll post my opinion, comparing/contrasting the two once complete.
Regardless, I do highly recommend trying the RealAir FDE. You won't be disappointed!