Thanks for the feedback - all very good and valid points.
I'm not too concerned with the winter capabilities of either car. I drive less than 5 miles a day (take the train to work), and have grown up with big HP RWD cars in Chicago winters. That being said, snow tires on either are a must, and I will continue to look into S4s (although I am concerned w/audi reliability, much more so than BMW based on the stories I hear, and I'm not too sure how I feel about upping the boost on an engine w/o forged internals).
No doubt that the "image" thing is concerning, though I like to think that the real question for me is will I care when I'm behind the wheel. If I love driving the car than I think I'll be happy, but the BMW image is much more fitting.
I definately agree that the the M3 would be a better overall DD - more space, more creature comforts, etc - but I need to consider the maintenance cost associated with the car as well as its fun factor as it will also serve as my "toy". Is the M3's practicality as a DD outweighed by its maintenance expense and its lack of torque and cost to modify? Again, maintenance on these cars scares me, especially considering that I plan to keep this car for 10 or so years. Could I afford it? Yes. However, I'd be pissed if I need to sink a few grand into an already expensive car to keep in working order. Any feedback on actual charges for regularly scheduled maintenance M3? In terms of fun, the car will only see street duty in the burbs of Chicago. These streets are flat and straight. How much of a hindrance is the lack of torque to having fun on these types of roads? The other part of the "fun factor" to me is tinkering in the garage. The cost of modding the M3 is insane compared to the GT500. Lots to ponder here...