Hi Brad,
I don't believe ESU has done anything one way or the other. I don't know much about them, other than they are somewhat of an enigma. I was in Ulm earlier this year (my wife's family is there) and tried to visit their place of busines. I couldn't even contact them to make an appointment.
I have their decoders in other locomotives and am very happy with the performance. As for the S12, I have no clue, and I am not an electronics type of person. Electricity....yes, solid state....no.
Hopefully other readers will share their experiences, so maybe we can track this down.
Buzz