Yes as Mono said-he would be in a very different position then Ceoli-but the emotions and feelings she brings up (and others on her thread) are all pertinent for him.
He doesn't have a way to know that his position IF he accepts is concrete. That's a lot for ANYONE to deal with. Just THINKING that you might be disposable is enough to set someone's teeth on edge in love and relationships.
Mono and RP seem to have gotten their train on a kick butt track-but in order to do that-YOU and YOUR HUSBAND need to be sure that you address the "third" persons needs, desires, fears, concerns as equally as you would your own.
As a wife whose in a V relationship I understand well all the risks my boyfriend takes in trusting in the permanence of our love and our relationship. Because when push comes to shove usually the third gets the losing end of the stick for the "benefit" of the original couple.
I don't know that I could ever BE a "third" because of that..... You (nothing personal I have as well) are asking a lot of this man. He deserves time to seriously consider if it's worth it to HIM.