I'm in a DADT situation. It's not my ideal, but it is what my husband feels most comfortable with. I'm the one who feels the need for relationships outside our marriage, he doesn't. I dislike how it attempts to limit my ability to be emotionally attached to someone else, and to treat them like a part of my life. My husband works a lot, and doesn't come home until late, so I have plenty of time to give to someone, and hubby is good about not ever seeking evidence or even asking me where I've been (I don't stay out all night.) It is also understood that if someone comes along that I feel real emotions for, I will want to change the gameplan.
I agree with the statement that this will work well until it doesn't. It definitely isn't how I want things to stay, but we only opened the marriage a year ago, and I am looking at this as growing pains, not our ultimate destination.