I know I've seen the answer to this on here before, but I can't remember and it was too long ago for the search.

Are the bows, designed for more speed, that much more efficient than the slower models, or are you really only get a similar percentage of the energy you put into the draw, back out on the shot?

If one model shoots a 500 grain arrow at 230 fps at 60lbs and another bow shoots a 500 grain arrow at 230 fps at 70lbs, then isn't the energy going into the draw, about the same? Without a doubt, some cams seem easier to pull than others, regardless if it's more peak weight.

Another question. If the energy going in, is about the same, then wouldn't a similarly spined arrow be required for both, even though one is 10 lbs more peak weight?