John 1's comments provide one view, so in disagreeing I mean no disrespect to him. First, let's dismiss the "space" issue: both the 2Ce and the 3A speakers have the same size "footprint". The only difference between the two speakers is that the 3A is about 8" taller -- otherwise, they are the same width and depth.
As regular readers of my posts know (perhaps ad nauseum), I have owned the 2Ci, 2Ce, 3A, and now the 3A Signature, and I have listened extensively to the 2Ce Signature, so I have a pretty good idea about the relative strengths of all of these Vandy models.
Given a personal choice between buying a new pair of 2Ce Signatures and a used pair of 3A's (assuming the used 3A's are relatively new and in good condition), I would advise you to buy the 3A's. I strongly believe they are a signficantly better speaker than the 2Ce Sig (more transparent, a bit more neutral, better mid-range, deeper and tighter bass, and better soundstaging), and they offer a cost-effective upgrade route to the 3A Signature.
If you are concerned about buying a pair of used 3A's (which weigh about 100 pounds each, and can be moderately expensive to ship any distance), try to find a local seller, or contact a Vandersteen dealer to see if they have any demo models or trade-in 3A's on consignment. Audio Connections (in New Jersey) often has used Vandies for sale (acquired as trade-ins), and John Rutan is the man to talk to.
Your current amplifier provides more than enough power to drive either set of speakers, assuming it is a "high current" design (i.e., has a large power supply).
