I have both a 51# recurve and a 70# longbow. I shoot the same 650 grains out of both, and I can tell a noticeable difference in speed and penetration between the 2. I have found sessions shooting with the lighter bow to be helpful when working on form. The only challenge I have with the 51# is not being able to get a clean, consistant release, which I know is a form problem, but it is really helpful for feeling coming to fulldraw, and back tension. I find shooting 70# requires me to practice from 10 yards and in to focus on form so on longer shots I dont short draw the bow, which is a nice way to say target panic. From 15 yards in I am money on form, but when I get to 20 plus not so much, with the lighter bow this is not a problem, but my release is.