I'll be a bit contrary on just one aspect: all the accelerations on more or less level ground. If you're riding with people with lighter bikes and you're matching their surges I think you'll fatigue more, but otherwise it's not noticeable with respect to overall effort. Yes you can feel a faster acceleration from start, but what it really amounts to with the heavy bike (once you get acclimated to it) is a longer period of acceleration at the same effort to get up to speed. Slightly longer, slightly more energy used. Over the course of a ride the difference from just this part is trivial.