The quarter mile times aren't wildly different, but from what I've seen a standard valver is normally around the 16 second mark, a 172/182 closer to 15. (lets not forget that a second at 85-90mph = over 35metres (10 clio-lengths?) assuming identical reaction times, ).
Dan_mk1, good times bud, you obviously have a good one, and lightly modded iirc?
I personally think it would be very close between a Cooper S and valver in some situations, i.e. straight line blast when the valver is on cam and some b-road style twists.
However, that's just it about the valver (having owned one for 3 years), they aren't very good off cam meaning you can easily be caught out, and if you load up with a couple of decent sized passengers then you WILL struggle against a lot of 2.0litre+ repmobiles (as I found out to my embarressment a couple of times).
Great fun though - I want mine back!