Kyosho want to sell planes. Lots of people have 46 size engines laying around. People are more likely to buy a plane that uses an engine they already have than need to buy a new one. Remember to make money they need to sell them to all types of modellers, not just the 3D fanatics like us on this forum.

Will the Flip perform on a 46 FX? Probably will if proped right (dont have one myself). In perform I mean will have enough power for hovering. But it wont have the vertical performance that many people now want.