The tires are fine to drive, I honestly can't say that they're significantly different from the Michelins they replaced. Although we do know that the Pirellis are stable at 110mph

About the cleaning, I actually never addressed it again. Seems that all the methods worked equally well, so the NZB way wins

Of course, the car hasn't been in the rain once, so who knows how durable the treatment really was

Update: The crud is starting to show through on the NZB-treated wheels. Oh well.

Also, the tires do tend to flat-spot (much more readily than the Michelins) if I leave the car sitting for more than a couple days (which I do) (which I was warned about) (which I do anyway).  But it works itself out in a couple miles, typically.

Finally, I still can't say how they perform in the rain