I can't really follow you here, Stabbey....
Let's take the situation in wich I join the host's game who has played with 2 characters in SP mode. So I will take over one of his two characters res. his second character. So I can't play with any of my own characters (the one from my "own" game). Why should I want to save any progress made with the host's character?
So for "progress-driven co-op" it only makes sense if I play with a partner a whole campaign together from the beginning. There is no possiblity to choose between SP and co-op mode with savegame progression. Or not?
