Yeah, I think mediation is inappropriate in an abusive situation, but for your garden-variety alcoholic, it can work. There are a lot of up-sides, and one of the biggest, to me, is that you get an agreement out of it (if it works). It's harder for him to play the victim card when the settlement is something he AGREED to.
I think it is definitely worth a try. If it isn't going to work, you will probably realize it early on, and you can then move directly to Plan B.