Correct me if I'm wrong, but are the MPSS not Michelin's highest performing summer tyre, or have I missed something?
No more so than the 452 are Falken's highest performing summer tyre, or the RE050A Bridgestone's highest performing summer tyre.
To avoid confusion, if a tyre isn't specifically designed for sub 7c usage, then the trend is to start calling them summer tyres. The amount of water the MPSS is designed to shift makes it the best all-year round tyre you can buy.
Are they M&S rated? If not you will have a problem today as its snowing. I don't get the MPSS are amazing compared to 452's thing. The GSD3's or F1A2's are amazing compared to 452's. Plus the rate 452's wear the MPSS will probably work out the same price over time.