Steviej,
I have the SP Sport A2's on my 92 ES300 for the past two years with about 43k miles on them. I haven't had any trouble through all the snow, slush, and rain that's befallen the Washington, DC area these past two winters. These are a hugh improvement over the previous D60 A2. Even with over 40k mile, there's still considerable tread to last me through the summer.
I've had even wear on all four tires with regular rotation. I'm not very agressive on these tires, but when I do push it, the tires never fail to hold and provide feedback when at their limits. I do not have any experience with the Continental Extremes, but I have tried the ContiTouring Contact CH95 with no complaints except for low treadlife.
Just my 2 cents.