One of the effects of rim/tire weight that's often ignored on BF is just how much it impacts handling and feel. Our spinning wheels act like wheels in a gyroscope - the heavier wheel and the faster the spin, the more it's going to resist changes in orientation (the next time you change a tire, spin your wheel while holding on to both ends of your QR or TA - try to tilt the tire and note the resistance. Then take off the tire and try it again with just the bare rim - big difference and that's at a relatively low rotational speed). If/when you get out of the saddle and rock the bike back and forth under you, whether you're climbing or sprinting, the difference between lighter and heavier wheels/tires can be readily felt. A difference in initial lean-in when cornering can be felt, too.