I was so unsatisfied with the P7 All-Seasons that I headed back to the dealer Monday. They corrected the problem and replaced the wheels and tires with the proper staggered wheels and Summer P7s. Oh, what a difference...night and day!
The confidence in cornering I had when test driving has returned. I've also noticed an improvement in braking (as suspected). Understeer has not been a problem. I don't plan to test the handling limits any more extremely than I have so far, so understeer is no longer a concern of mine.
I am happy enough with the Summer P7s that I will not get rid of the runflats. I also don't want to give up cargo space for the donut.
In my opinion, it is better to run Summer tires and get a separate set of winter tires if your climate dictates it. The all-seasons are a compromise in every sense of the word.