The 17" S-spoke wheels are the heaviest OEM wheel that MINI do.
The ride is compromised by two aspects:
(i) The run-flat tyres have strengthened side walls to permit extended running when flat. As such, there is less flexibility to absorb any road shock. This is applicable to both 16" and 17" wheels.
(ii) The increased mass of the wheel, affects the handing of the car, due to the increase in un-sprung mass. This affects the suspension's ability to react to bumps and undulations. This increase in mass will also affect the acceleration of the car initially, as there will be more wheel inertia to overcome. Having driven both wheel sizes back to back, the 17"s are more prone to tramlining over broken up / tar-banded / ridged surfaces.
The trade off between 16" and 17" wheels is this.......
16"s have less mass, hence will improve the ride, handling and acceleration, albeit at the expense of the "looks"
17"s have a slightly wider footprint (205 vs 195), and visually "look" better.
You pays your money.....you takes your choice......!!!
If it's helpful, all the BMW press cars are fitted with 16" wheels........I wonder why that is?
Robert (16" 5-spokes by choice!)