well, I do have a 916AT that is pin down, along with a 716c with the same drilling ( pin under the middle finger and MB off in a strong position )... I have a 715T that has the pin in the ring finger and MB in a strong position... And my 811A is drilled the same as my 715T...
So I sometimes wonder if getting a " new " ball will just be over-lapping other stuff...
honestly, my idea is if i get a 503T is to use a similar drilling as my 505A, and then with the 300A do the same thing.. So i have a bit of a same / but different look with these balls..