Will be ordering an Electroclash 500S in Sept and am attempting to finalise spec. Is there a discernable difference between 15" and 16" wheels in terms of Comfort and Economy? I quite like the standard 15's that come with the S but also quite fancy the black 16's with the electroclash. AFAIK 16's knock about 4 or 5% off economy but is the ride noticably harsher?