Bob, I am going to regret this post because I may touch off another speaker war. We lost a lot of A'gon members at the last "Clash of the Titans" (pun intended). RIP guys. :( Btw, as an aside, there's a post currently running asking members to list their favorite speaker. There's more than 1300 posts!!
Ok, I am taking a deep breath and am ready to take cover. You mention that you currently own the Paradign S8, presumably version 1 (Go-Pal tweeter). Since that time, Paradigm has made numerous changes and improvements to the Signature line, probably the most significant being the beryllium tweeter. The new S8 (now version 3) has received rave reviews, e.g., Marc Mickelson, May 28, 2010, TAB.
Another point is that the S8s (v3) are considerably less money than the Vandy 5As, if purchased new. (I guess that means the Vandys and B&W speakers you list MUST be better than the S8s because they cost more.)
All I'm saying is that you may want to treat yourself to a listen. Having said what I did, perhaps another "speaker skirmish" can be avoided by saying that the other speakers you mention in the OP have great reputations and should be seriously considered.
Cheers