I loved the Pilot Sports in my previous car and am looking forward to getting the Michelin Super Sports on my Panamera in the near future. If you decide to replace the fronts with Michelin, and leave the rears as is for a while, you should be fine. Just get use to any changes in driving behavior. If you don't like the way it handles, then just order the other 2 tires.

 

Mixing tire types is one of the fundamental things you DON'T do to a car. Sure, you can run the car with completely bald tires if you want, or you can run your summer tires in winter snow, and yes the Panamera will 'compensate' for this. High Performance Summer Tires have very different handling characteristics. If you put Michelin Pilot Super Sports in front, and let's say have Michelin Pilot Sports or Pirelli P Zero's in the rear, you'll get more oversteer because the Supers are stickier. You could get in a dangerous situation with a setup like this.

Why would you buy what is arguably one of the best handling sedans on the planet, and then intentionally compromise its handling?