Might be a little late to the party, but I figured since I have experience with the tire in question in the OP, I'd throw in.
I just recently had a set of Eagle GT 215/45/17's mounted on my wifes' Cooper S. I'd have loved to have gone with a dedicated summer tire, but we were in a pinch because I blew up a tire doing a burnout in the walmart parking lot, and she needed to get to work. It was fun though.
That being said.... I dig the tire. It feels pretty good for an a/s tire... and didn't seem to negatively affect the handling on the car. I had runflats on it previously (stupid germans not giving me a damn spare...) and it took a little getting used to in that car, having more sidewall rollover than previous, but the definitely stick pretty well. I'm anxious to see what they'll be able to do in the winter, as that little bugger was a TANK on the old tires, and these are far better than what was on it previously (205/45/17 RSA EMT for those interested).