[Mini_me]

This is a question for those who have driven both the Cooper and S for more than just a quick test drive.

I had an S for a couple of days and even though it was a demo car, it seemed smoother than my Cooper engine (which in turn is a lot smoother then the demo cooper from the dealers).

[MiNiGuY]

Drive both regularly.
Would say that overall the S engine feels smoother yes helped in no small way by the Getrag box it is mated to.
It feels larger than it is also although the actual gearchange feels clunkier on S.
However the one and cooper exhibit less of a delay from the electronic throttle. If you push your foot to the floor while idling along in first, the cooper S has a very small delay which isn't present on the one or cooper making those cars feel more snappy or responsive on the uptake and they generally feel looser and more revvy too - Not particularly a bad thing, but for the sake of the question it all adds up to make them feel more harsh than the S overall.