I faced exactly the same choice not too long ago.
We have a 2002.5 S80 2.9 with the 17" wheels.
When I was looking for a replacement set it came down to a) going to a 235/45 to get a broader selection, or sticking with the 225/50.
I had a friend who had done the same thing with an Acura (gone to a wider tread width and a lower aspect ratio) and had experienced some uneven wear and a few other problems.
We decided to stick with the 225/50s, which left us with either the Pilot Sport A/S at over $800, or a Bridgestone Potenza RE92. I had the exact same size Potenzas on my 2002 Nissan Maxima, and was less than impressed with them, so we went with the Pilot A/S.
So far,we have 8700 miles on them, and are quite impressed. Both the dry and wet handling is slightly better than the OEM Michelines, and they also seem a bit quieter. No undue signs of wear or anything unexpected.
We have not yet experienced any winter weather with them, don't get a lot of that here in Texas. We do get some pretty serious thunderstorms, and the Pilots did quite well in some very heavy rain, high wind, standing water type conditions. No tendency to hydroplane or lose traction.
All in all we're very happy with the Pilot AS, yes they're pricey, but I consider it money well spent.
BTW, when we priced them, Discount Tire actually beat CostCo by a few bucks, I took a copy of a Road and Track magazine to them, which had a mail order price the store manager matched. I later was told he wasn't supposed to do that, but you might give it a try.