They both have different virtues I've owned the S1 right before the newest virsions,they had wonderful natural midrange,but they didnt play very loud before they started chuffing out of ports.The 602s are the better overall speaker they can play ungodly loud and play very deep in the bass,mate them with something warm so their topend wont be bright and make sure you have plenty of power all B&Ws like power.
I auditioned yesterday the 602s3 tyhe 601s3 and the RS1
In deed the MA RS1 has a lower frequency response that is notisable, nevertheless the bass notes sounded with out much definition compared to any of the B&Ws.
The B&Ws sounded with more clarity, image and life
I will go for the B&W601s3, i liked the sound in a small room even more than the 602s3 and will aslo save some money
Make sure you try the B&W DM 600 S3. Smaller, prettier and cheaper than the 601, they are very well balanced and ideal for small rooms, though still powerful.