I think the assumption that is being made is that whatever motor is being installed will be flown at full throttle for some length of time. I wouldnt believe this to be the case. I think with any motor over 18lbs that full power would only be used for short durations such as takeoff or vertical manuvers.
But put a 12-18 lb motor on a Bobcat and you'll being using full throttle much more aggressively especially with the smaller. Not a favorite combo for me. However I think the new Artes Rabbit and Bobcat will be a blast.
IMO
Scott