Vandersteen 5a carbon vs 5a

i owned the 5a for five years or so. A great speaker and certainly a hyper good value at the $9-12 K range you see them being sold at....
yes I have heard the 5a carbon as well and find it sublime.
I own 7 mk2 with the M7 amps as well.
the carbon fiber/ balsa drivers are so low in distortion they are something to be appreciated with time......listen for ten twelve hours at a stretch.....amazing fatigue free clear pure water like flow....I cannot describe it...

i am actually thinking of trading my Treo CT ( good as they are and they are good.better treble than my 5a ) for the birdseye maple 5a carbons Sunny has.....

you might hear some 5 a owners making a fuss about not being able to hear the difference....and yet singing Richards praises....
I am 200% sure he is right with the new drivers....

Price aside, the 5A ought to be readily upgradeable to the Carbon 5A.  Or what am I missing?

I believe there are other issues than just installing the new Carbon Tweeters that make it a no go.
I own the Treo's and would really like to upgrade to CT, but it isn't in the cards.
B

according to review in TAS the upgrade from 5a to 5a Carbon is available only to original owners

I am an original owner of 5A's and was going to send them back for the update.  My wife and I listened to the 5A Carbons and although the electronics were different, and maybe an unfair evaluation - but we both agreed they sounded so similar, it wouldn't have justified the cost.  MAYBE....a bit more clarity in the mids, but not sure.  If I were to buy new, I would probably get the 5A C's, but I'm quite contented with the speakers I have.