The alloyed Roadster is slightly narrower in the track. The lighter wheels will make a difference to acceleration and bump deflection, so it should be a smoother ride, even though that's relative!!!!!!
I wanted wires because I like the look of wires more, and don't mind spending time with a rag. For a road car it only matters if it matters to you. The easiest way to reduce the 0-60 time, after throwing out the passenger seat, heater and spare wheel is to lose some weight. A couple of stone would probably be noticeable. I reckon that as a 10.5 stone 'athlete'

, I could keep up with a 15 stone bloke on alloys.
So there.