I think its just a personal thing my car is my only car and while up here the weather aint great I would like to arrive at the office not looking like I ran there. I bet as I track it more and more I will be wishing away those extra 15kg but at the mo I stand by my choice, although I do have my eye on those Ohlins!
Since owning the S1 I have been amazed at the importance of weight in a car (or rather the lack of it). My std 190 S1 will pretty much keep up with a 240R S2, go figure.
Ian