An interesting observation! I have been on the 319/320 for about five years now. I have also flown other type jets, and I can't say I have really noticed any real difference in the time to roll, for any of them. Perhaps there is, I have never really noticed, but, I do not do as many expedited T/O's as you clear to be done. As for the second question, I think most pilots will try to accomidate, but when that request comes too late, or even at an inappropriate time. ie. Right at touchdown, before we have time to slow, I tend to ignore any requests.