I'll spare you the tired truisms about all seasons being no seasons, but all the same, you're going to get better performance out of a summer only tire with minimal headache in your situation. All season tires have their place to be sure, but it's not in an area that hardly ever sees solid precipitation, or even temperatures below about 40. You might have some tradeoff in treadwear with a summer tire, but you'll more than make up for it with added safety margins for traction, especially in wet conditions.
Your OE tire is an all season Dunlop that is fairly expensive and gets pretty crappy reviews on Tire Rack. For practically the same money (at least when the Dunlop is on special as it is now), you could get one of the highest-rated tires that they sell - the Michelin Pilot Super Sport. Its 300 treadwear rating is a little lower than the Dunlop's 340, but I wouldn't expect drastically less life out of them. Right now the Bridgestone Potenza S-04 Pole Position is on special, which would save you a little over $200 on four tires versus either the Dunlops or Michelins. Its treadwear rating isn't quite as good, but if that's really a concern for you, there's also the Continental ExtremeContact DW which would still save you about $125. There are a few others that would save you some money versus stock, but those three should be on anybody's extra-short list of tires.
And if you're really, truly insistent on all seasons, there are a couple of new models that look promising - the Continental ExtremeContact DWS 06 and the Yokohama Advan Sport A/S.