The 21s might do a bit better in a drag race, just because the tires for the 21" wheels are sticky 'Ultra-High Performance Sport' summer tires, whereas the tires are the 19" wheels are considered 'Luxury Performance Touring' all season tires.
I'd expect to see a more significant difference in handling, especially from a P85 or P85D. If warmed up properly, the 21" tires will allow the car to run faster through the corners and maximize the lateral acceleration capabilities of the suspension (both due to the stickier rubber compound, as well as the shorter stiffer sidewall). On a track, my money would be on the car with the 21s.
Of course, all of the above is dependent on warm weather and dry road conditions. If the road is wet, or the temperature drops down near freezing, the all season tires would likely prevail.