Correct me if I'm wrong, the ISF only comes in Auto no? I think your Z is auto so won't be an issue for you, a club member switched to one, looked nice, nice performance.
I personally love the A5/S5 but in Montreal, the are everywhere along with the 335.
S5 will be comfortable for your travelling, its powerful, and classy as hell. If you have an issue with seeing lots of the same car, id go ISF...more rare and a good car. I voted Audi
