The direction of the development of Lionel's AF line toward a scale friendly stance is very encouraging and exciting. For myself, a more scale influence is a positive thing and the possibility of offering a DCC add on is very appealing.
Two questions come to mind:
1. As the DCC board would be an add on to the Legacy board (as I understand your post), would the primary power source still be AC? If so, this would be a distraction for me.
2. Would it be possible to offer the DCC plug in to a Legacy less, DC powered, locomotive? This would be the most attractive alternative to me.
All things considered, S scale much better off with the current direction Lionel is taking in the S market than without it. I applaud your efforts!
Roger