Should have read this thread a few hours earlier...

Just ordered a new PR4 front to replace my old one. Toasted the rear in, err, a bit of 'fun' riding and had to put on a stock Dunlop, but the combination actually doesn't do badly. Showing that, in actuality, the rear has much less affect on the handling that the front.
Got about 14,000 miles on my set (I'm light), but the front PR4, while not yet at the wear bars, shows quite a bit of cupping.