I have P3D v1.4 (Academic Version) and all, except the 777 v1.2 work perfectly in P3D! There are tweaks that need to be done to get them to work properly, unless you use the FlightSim Estonia FSX to Prepar3D Migration Tool, which does it all for you as if it was installing in FSX.

I run both FSX and P3D, so IF I install using the Migration Tool, I always install to P3D with the Migration Tool, then into FSX proper, that way, all  the shortcuts in the Start Menu are pointing to the FSX installation. As far as I can tell, the ACE doesn't (at least for me) work in P3D.

There is a Prepar3D Legacy Mode, which will allow the CS 777 v1.2 to work in P3D, but P3D crashes every time I use it. It seems like you shouldn't run it in Legacy Mode if you have FSX installed on your computer as well. :(

[edit]Seeing as I have the Prepar3D Academic License, it is highly likely that I will have to by a new license for Prepar3D. And if that is the case, I will be buying the Professional License! So it will cost me $US199 for v2 if I have to buy it again. :([/edit]