I have the HM frame and to be quite honest, I can't tell the difference between it and my brother's non-HM . The HM is supposed to be stiffer, but I can't feel it, and I'm a CAT-3 racer. Maybe if I raced on the non-HM, it would make a difference. It's the same frame except they added Hi Modulus carbon in key areas like the bottom bracket and headtube areas. They were able to shave some weight due to this, but in the end, that can be negated by some component changes. I don't think that the average cyclist will notice the difference. By the way, HM frames are in the 700 gram range weight; the non-HM isn't that much more. Things sound like a lot more when you're counting grams on a particular component. Consider this: If both bikes you are comparing use a different wheel/tire combo, the performance will be different.