Also keep in mind that SS+ was 'watered-down' for the American market in 2003. The original (and best) SS+ was quite firm. I've driven Coopers with all of the different combinations. Basically the SS->SS+ sorts out body roll, it's the wheel & tyre combination that makes the ride harsher. The benefits of the bigger wheels are cornering and grip in the dry (and appearance), the disadvantage is 'ride comfort'. Saying that, you can make the ride softer with 17 or 18" wheels by using non-runflat tyres.