You'll find lots of discussion on this subject if you have a hunt around
Personally I drive a Cooper and am more than satisfied
I've driven an S too but it hasn't made me think I really need to have one. Sure the supercharger sounds nice when it clicks in but there's not so much difference between the two models in overall driving enjoyment
I'm not too much help with heavy loads but I have driven around with a full load of passengers. And I'm pleased to report the Cooper had more than enough power to cope
