I tested a 3 series (both sedans and coupes) with and without sport suspensions, and it felt different to me. In fact, I could feel it noticeably. However, I pay close attention to these things because I utterly, absolutely love "driving feel" in a car. In addition, the sport suspension-equipped vehicles normally have larger wheels; I'm not sure how much that affected the feel; I'm sure it did at least partially.
I've never tested an x drive vehicle before now.
After my experience, and after learning that RWD with winter tires isn't really less "safe" than an AWD car (based on C & D articles, those who seem like x-drive experts (not the biased ones) on Bimmer forums, etc., I decided it was worth the trade-off to get my sport suspension.
I really think it's trade-off. You can't have the best of both worlds. Need to make a choice. I live in the city, frequently drive melted highways, and drive much more often on melted roads here in the winters than in conditions that I experienced today.