Double f, I like to use engines on the lower end of the recommended range, that lets me be a pilot instead of just a throttle jockey. I got heck for this the very first time I flew a plane. I had a Kombat 40 with the 60" wing option and had an Enya .46 MKII. Everybody who looked at it said it wouldn't fly because the engine was too small. Well, somebody forgot to tell the engine, it flew just fine and it was 100 degree day in about 1991. That was my very first flying lesson.