Picked up a set of 9.5 / 10.5 matched with PSS 265/285s and the difference over my stock 18s is definitely noticeable. Ride is smoother (the first thing I noticed), response is better, and I can feel a slight increase in acceleration. With the EDC on comfort, these wheels ride smooth as silk while still responding immediately to even the slightest input.
I've always thought a great set of wheels and tires are the best investment to improve your car and this seems to be true yet again. How can you go wrong with something that will take every characteristic of your car and make it better? Money well spent.
2009 e92 M3 - AW DCT - Apex Arc8s - Corsa