Hi Nick,
I bought a pair of the original 3a's that were made in France. I waited a good year before coming across a pair on Canuckaudiomart. The seller was upgrading to a pair of 3a MM De Capo's. I had listened to the De Capo's numerous times and really like them, but I wasn't prepared to drop $3k on speakers. From what I understand the MM's made in Spain are best avoided as they had serious quality control problems.
The best way to find a pair is to keep your eyes peeled and simply wait it out if they are something you really want. I will never sell mine, ever. That's the problem though, people tend to hang onto them. They can apparently be upgraded by replacing the internal speaker wire as well as replacing the cheap capacitor and cheap binding posts. The cabinet is not as good as the De Capo's, but the woofer is pretty much identical to the De Capo with the absence of the phase plug.
I believe if you keep them at least 26" off the floor that the phase plug is unnecessary, as if I recall correctly the 3a L'Integrale didn't use a phase plug but had the same woofer and I believe that was the justification.
This is a great speaker, but unless you really want one you'll be expending a lot of effort for not enough return, so I guess it's up to you!