Sorry Fred I have to disagree with your J3 analogy. My first flight was in a J-2 with a 37 HP Kitten engine. Takeoff
climb and cruise were all the same airspeed. I worked for Piper for a few years and can tell you that the PA-18A would carry up to 700 pounds behind the pilot in the dust or liquid hopper. More horsepower in the same basic design will make a whole bunch of difference in performance as well as weight carrying ability. The glide angle and distance was also greater with the PA-18, however you would hit harder because of the increase in airspeed. It was a ball to fly and to this day I have never flown anything that I enjoyed more. My days as a pilot of anything more than RC passed a few years ago and I still miss punching holes in the blue. I wish I could say the same about my models but I never scratched a 1' = 1' scale aircraft.
Best regards - - ballgunner