I know you don't want the cookie cutter answers but I do think those are the best place to start.  You get peace & harmony in the household.  The better communication, a deeper connection, a better more meaningful cohesive us.  We get to be friends again, companions, lovers.   Things we've been missing for a long time.
You gt a way to deal with me.  To forgive an let go.  No more hiding behind anger or frustration.  You get to help me be better, for me & for us.  You get a wife who is at peace, content with the world instead of trying to control the chaos.  You get a happier, well adjusted (most of the time anyway) me. 
You get a cleaner house.  Though not perfect, it's better than a few years ago.
You get final say, for us, for me and for our family.
I hope you get peace and contentment.  I hope you've found love and friendship again.
So that was my answer.  It's not a great answer to his question and I still hope he finds out what he gets from DD without me telling him.  I love him and I want him to feel the same benefits I do.  Our path has not unwound itself yet and I think we may have made a few circles around the same tree, but I know the decision was right to go down this road.