If you're happy to spend that kind of cash on tyres that you want for performance (and good on you for doing so), then you'd do just as well to grab a set of the 18" Rays and put MPSS on them. Yes, it won't be the cheapest option, but it's the one I'd recommend.
In terms of comfort, you may well notice a slight reduction given the smaller sidewall. However, that will be massively offset by the fact the Rays are significantly lighter than the 17" wheels (5lbs a corner!) so your car will feel lighter and nimbler on it's feet. It'll also accelerate quicker, brake in shorter distances, use less fuel etc. Basically, the best of all worlds!
I'd expect ride quality to improve, tbh.