Mine started on the Michelins and I now have the Pirellis. My butt dyno tells me that the Pirellis are a tiny bit better but not materially. I definitely do not think it is worth spending tons of money to change them unnecessarily. Note that even on the all season Michelins there is enough grip to be competitive in auto-x with faster cars on better tires.

I think the Pirellis ride a tiny bit smoother, but my impressions might be tainted by full tread depth vs heavily worn tires. I also think the Pirellis increase the steering effort a touch but again, not by that much.

I hope that helps!