To add to what I posted earlier having given it some very spirited driving on Welsh country roads...
The much bigger gap between C and S mode is fantastic - I can actually use either now depending on my driving style, whereas I only ever used to use S. Eco with very low revs and insanely impressive fuel economy (30mpg+ is seriously impressive with the cylinder deactivation considering it is a 5.5L V8). S mode really aggressive gearing and better holding of lower gears.
The biggest plus for me is how much more usable the R172s power is. Even in our cold winter with salt on the road and the same make of tyre, I am managing to get much, much more power down and with significantly less traction control coming on than in the R171...I find myself trying hard to get it to come on now rather than trying hard to avoid the wheelspin. Combined with much more responsive paddle shifting in M mode and rev matching (OMG those throttle blips!!!), the R172 really is a dream to drive. Without the performance suspension it also bounces less over the bumps and feels so much more settled.
Can't complain about having the top down in the winter, with air scarf on low, heated seats on low, heating relatively low and being lovely and toasty in the cockpit with minimal air intrusion.
Just need to replace my private plate with my new private plate once my old plate has been assigned. Why oh why didn't I just get my new plate before the dealer submitted this batch of paperwork