Vandersteen

IMHO, not enough to justify the price increase. YMMV!

In this particular instance you would be wasting your money to allocate it toward electronics when for $2K you could move from the 2CE to the 3A. That from a former 2CE owner. If I were in your position and could afford the 3A I wouldn't dream of opting for the 2CE. 

Very few manufacturers in the industry give you more for your dollar than Vandersteen. When setting up a rig that will be around for a while it's penny wise and pound foolish to opt for the lesser speaker, especially when Vandersteen gives so much for the price. 

It would take a significant investment in fine gear and cables, maybe on the order of an additional $5-10K in components, and perhaps even more, to have a 2CE outplay a 3A. I'll keep the ball rolling; YMMV

@bdunne,
I assume you are considering buying used. So, cost differential would be minimal.
In any case, the biggest difference between the two models would be that the 3a sigs would have greater bass capabilities.
If you love Vandies like I do, then the next best upgrade would be to add a pair of 2w(q) subs which will bring you almost equal to a pair of 3a sigs.
(I upgraded from the 3a sigs to a pair of Treo's and use a pair of 2w subs. Mr. V. says it gets me to 90% or a pair of Quatro's-These are non-CT versions). So, if you want to upgrade in the future, you can still keep the subs.-Which, by the way, are the best subs I have ever used, despite not having a 'q' adjustment.
One of the things I didn't like about the 3a sigs was the footprint. The Sound Anchor stuck out like a sore thumb and made positioning much more difficult that the 2's and Hence, my move to the Treo's.
You should PM John Rutan at audioconnection (his store and Agon ID). He can give you the best information. And, he's a great guy, too.
Bob

Had 3a sig for about a decade
i am fairly familiar with the latest 2CE sig 2 as well as 2 CE

i would ask what music ?
what room ?
ability to get both off the back wall ?
and I believe very important what amp ?

the 3 a soundanchors are monsters and work incredibly well, wAF not so much

go listen to both
bruce in San Diego stocks both and his associated gear and setup are excellent 

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