There's a goldilocks type phenomenon going on here. Pretty much all steel frames are going to feel about the same to very light rider, in that they won' flex at all; and pretty much all frames will feel the same to a very heavy rider, in that they'll all be too flexy. For riders whose weight is somewhere near heavier end of the normal range, choice of tubing seems to make a big difference. I weigh 165 lbs and haven't yet found a frame that actually feels different from all the others.