If the pull on the upline was as good with a 27-10 than a 26-10, that would be good, losing a little speed in the strait and level may not matter so much for IMAC. It could also give a more constant speed in the box and the need for less throttle management in maneuvers.

However for the ultimate power out of hovers, or stop and go flying (3D), or at the other extreme air racing one has to squeeze all one can get for a particular motor, and prop combination. I think it all comes down to what we are attempting to do.