Wow! Cool. That's encouraging, though Azumo already has a very long tail - and growing... His body though is smaller and more slender than my friend's betta, so I think he would be 6-9 months old.
Yes, sometimes I feel that the long tails get heavier for the betta to carry as they age, which may cause stress. The plakats, with shorter fins, perhaps do not age so quickly.
The one picture I could dig up, not an especially photogenic fish. But I felt sorry for him, the gimpy ones weren't being adopted. He's outlived his "perfect" brothers by about 2 years already.