Kkm,
I haven't listened to the Vandies in about six months so that's a toughie. Off hand I would say they are more similar than different. Both have the huge soundstage. As far as tone, coherence, etc. I really need to listen side by side. If I had $2000 to spend on speakers right now I would buy the Vandersteen CE sigs II without a doubt. You can pick up a pair of older ones for four or five hundered on ebay of Agon to give them a try. I bet you will love them. BTW, people say that the 1 series can effecient but I tried my 1B's with a 15wpc 6L6 tube amp and the bass was flapping all over the place. That amp can drive most other speakers fine.
Pete