I just got some B&W 603s3s for a song as the dealer was selling his demo models. Lightly used, and a full 35% off their sticker price. I happen to really like the sound.
The soundstage is excellent. So much so, that I occasionally get up to see if the center channel is playing (and LCR600 that I got at the same time, also deeply discounted).
I really enjoy playing the B&W demo disks that I have. I'm sure they were engineered with B&W speakers in mind as Abbey Road studio gives them to their B&W salespeople when they come over and tour. The dynamics are awesome, and the sound is detailed, tight, and very clean, especially when pushed hard.
I've never listened to the 602s, though, but they probably would benefit from a good sub (I've listened to some of the new line of 600 series B&Ws paired with a much better sub than the piece of crap sub I have, and they sound amazing.
With that funky aluminum bass driver on the 603, I probably don't have the missing mid-bass issues that you have with your 602s.