I have a pair of DM602's. Personally I would not go any lower than the 601's. I think the 600's have a 5 1/4 inch woofer, not big enough in my opinion. I really like the 7 inch woofer in the 602's. They sound great.
They are nice, back in the day I did end up choosing paradigm monitor series over them. I preferred the sound, *and* they were cheaper. I was surprised that I liked the digms better. Listen to as much as possible. B&W makes good speakers, and there are a few other good contenders in this range that you should explore too.