Interesting that even the term DADT seems to mean different things to different people.
The form of DADT that is unhealthy for me is one where one partner claims that another is ok with their non-monogamy but does not want to know another relationship even exists, much less who it is with or heaven forbid, actually interact with the metamour at any time.
Having different levels of comfort about discussing details within open relationships is simply that to me: different levels of comfort that are more connected to the individuals involved rather than the relationships. As such, I think those sorts of conversations are best left to negotiations between each dyad.
To me the difference is simple. If I call the house and your SO answers, will the phone be cheerfully handed over? If we are seen together out in public and it is mentioned to your other partner, will s/he be ok with that? If a medical emergecy occurs when you are with your other partner, will I be notified?
If the answer to questions like those is yes, then I don't define that relationship as a DADT in my lexicon, regardless of the level of disclosure beyond that bare minimum. My presence and our relationship are acknowledged and accepted and while that may not be my preferred depth of connection to metamours, it is a situation that doesn't feel inherently unhealthy.
If the answers are negative, then I really don't want to be a part of that sort of configuration because it makes me feel as though we are cheating, even if we technically are not.
One of the reasons I am out to virtually everyone in my life is because I like to talk about my life. It's far easier to simply explain once who everyone is instead of censoring myself when I talk about something that I did with rosevette or an event that the four of us attended or even conversation about the various kids in our family.
To participate in a DADT relationship would require me to restrict my casual conversations in fear that something I said might reach the ears of my partner's SO and cause problems.
I find that my partners mostly are not interested in hearing intimate details about each other and while I would be comfortable with such discussions, I don't really need them. But we do chat about the mundane things that happen in everyday life and that is something that I do prefer.
Perhaps because there was no "primary couple opening up" in any of my configurations, many of the protective rules simply never have applied to the relationships that are in my life.
Whatever it is, I am blessed to have found such a wonderful family of choice who share the same vision and values as I do.