The Pirelli's lasted forever on ours they were still at 5-6mm after 17k on the front, the rears still 7mm+. I used a puncture as an excuse to replace them all to Pilot Sports.
I sold the old ones off which covered a large part of the price, the difference is massive especially in traction in anything other than a dry road the Pirelli's would break traction up to 3rd/4th gear and in the dry traction control would fight it through 1st/2nd with the Michelin's it will very slightly spin/flicker the traction control in 1st in the wet and dead hook in the dry. That's before you get to the ride and tyre noise being better only thing would be the turn in was slightly sharper on the run flats with stiffer side walls.