Vandersteen

I'll give you some more info about my set up.  I have a REL B-1 sub (still have the VDS 2wq and loved it, but it was nice to be able to use the REL for stereo and HTS).  Amp is Moscode 600, preamp is Rogue Magnum 66, CD player is Quad CDP-2, TT is Luxman PD 441.  I already have the 2CE's for several years in my system and was wondering if I would take a big step up with 3A sigs.

I have 3A Sigs, driven by an Ayre V-5xe.  Killer combination.  That said, having recently heard the Quattro CT at Johnny Rutan's place, I would say that that is a big step up from the traditional Vandys (1, 2, 3).  If it is feasible to wait a bit longer to swing Quattro CTs, that what I would do (and would have done).  The Quattros would reward some upgrades in your front end.

@bdunne 

I agree with cedargrove, moving up the line to a pair of a pair of Treo's or, better yet, a pair of Quatro's, would be the way to go.
Regarding the move to 3a sig's, I would add another 2wq sub-which would get you into 90% of a pair of 3a sig's. 
As cedargrove mentioned, upgrading to an Ayre amp/integrated or an Atma-sphere amp will really open up those 2ce's.
Bob