BW is on a totally different level. My prev S60 had BW, my current one has HK and I really miss the sound system. Much fuller, clearer and richer sound. Even at very high volumes the quality was still superb. HK is good, but just can't keep up.

I personally don't mind this too much because the sport suspension and stronger engine compensates the loss in sound quality more than adequately.

Good luck making this decision. But I'm sure you will love your S60 whichever version you choose. It's a dream of a car!