If you are willing to spend around $800 ready to fly (less if you already have good high torque servos), then the H9 27% cap with a MOKI 2.10 is an excellent 3D plane. Very stable in all aspects of 3D flight that I have tried. It is as stable as my 31% edge and flys better in some aspects. The MOKI uses 0% nitro which costs only around $6.50 per gallon, so it is as cheap to operate as some smaller engines.

Greg