So my source close to Ludwig says that the shells are the same, as in "the shells are sonically the same."
the acro comes standard with acro lugs, the supra with imperials, and you can' t upgrade to tube lugs or a hammered shell on the acro.
They both come standard with a P-85 throw off, but you can upgrade to a p-86 on a custom ordered supra, while you have to have it installed after purchase on a acro.
The hoops are the same. the only real difference other than the lugs is the coating powdercoated vs. chrome plated.
My next big purchase will be one of these three. I thought is was going to be a BB or supra, but this thread has made me rethink my attitude towards acrolites.
If they are sonically the same, then it's going to take a great ear to tell the difference between a 6.5 supra and a 6.5 acro based on the difference in lugs and coating. I know there is a difference, but I'm not sure I could detect it.
I hope this helps.
PS: this also begs the question, "Is the brass supraphonic identical to the BB except for the coating?".