Mileage reports will vary off the scale. For me the PR2s and the Z8s are comparable (haven't tried the PR3s and don't think I will) in ride and handling. They're both good tires but the difference I noticed was at the end of their lives the Z8s felt better than the PR2s and that's the determining factor for me. The PR2s got flatter and harder and slid around more at the end. Both lasted almost 6000 miles which is incredible for me. It's funny, I'm so used to sport tires that I got tired of looking at these after 5000 miles and started to get the feeling like I should replace them but they just wouldn't wear out! I've never had an issue with straight line stabililty, road noise or comfort but I'll be honest, all I care about is cornering grip. Both tires work great in the rain but then again I've used sport tires that were great in the rain as well.
I know I'm a minority on this forum but my preference is the Z8 and definitely in a 55.