Damn, I'm in the same boat. One of my POS tires is punctured, so I'm taking the opportunity to replace them all with something better, in the 205/50/15 size too. The 712's are what I was looking for, but are $276 shipped from TireRack. A friend of mine works at a wheel/tire shop and he can get me 4 Falken 512's for $200 out the door, but the all-season thing has me miffed - I'm in Miami, it's rarely cold and never snows so I'm looking for something that's more along the lines of a summer tire. He runs the Azeni ST-115's in his EF hybrid Civic, loves em, and recommended them, but it seems that Falken doesn't make it in 15".
Are the 712's worth the extra $76? I drive really spirited with the occasional hard launch at a stoplight, but don't really road race or autocross.