I can't relate, but since you have known these people for years and since you really like them, moving may be the way to go ... maybe.
Being friends is great, sleeping together might be great and euhm maybe babysitting could be great ... but for how long? Then again you say "D is not sure how long-term she wants this to be" - in the future that may mean that only the "friends" and "babysitting" prospect is left ... are you cool with that? What if irritation sets in? You seem to be happy living where you are, only thing you don't like is the drive to your friends. To me, that doesn't sound like a compelling enough reason to move.
You have always known and interacted with these people as friends and recently as "lovers" and/or "sex partners", not as (good) neighbours. So for the moment you're just two distinct couples who like each other, with each your own lives and at least in regard to family planning, it would appear that you have a different mindset.
In the long run these different wishes and interests could interfere with your own and their lives ... so frankly it sounds a little nuts to me, then again: "no nuts, no glory!"
