Last year, MotorTrend did an extensive article on front vs rear drive performance. They tested a GXP against an Infiniti G35 and a WRX. Of note in the article was the circumstances as to how GM came up with the wheel/tire combination and sizes. Apparently to offset understeer, which, because of the 67% front weight bias was huge on this car with equal sized tires all around, they started playing with sizes, and came upon this combination as the final answer - only problem, no one made a "matched" set in these tire sizes. They shopped it around and only BFG was willing to believe in their concept. Once setup, it performed well beyond expectations, or so almost all the articles I've read report, and the steering is fairly neutral, with minimal understeer at higher performance levels.
Of note though is the fact that BFG makes the tires, which I've only seen reported last for 25k miles. I have to admin these tires are really sticky, and I've pulled, according to my onboard display .90g, they weren't screaming too loudly , but the handling was tight and right on.
Now, if Michelin only made a set for wet climates like Washington's.....