I read somewhere that the average weight bow used by Olympic archers is 38-39#. I personally like a 40# recurve, or a 42-43# reflex/deflex longbow, for 3D. The extra couple of pounds on the longbow helps offset the slightly lower speed I get out a longbow because of inherent differences and because most longbow tournaments I enter require wood arrows. I find that carbon arrows that are easy to tune are readily available for 40# recurves, and they have a relatively flat trajectory out to 50 yards. This becomes more difficult at weights under 40#. Even at 40#, I get a few bounce-offs of 3D targets that have been refinished a lot and have built up a hard surface. We give credit for bounce-backs, if someone else sees where they hit, but not skip-offs. I think some of my skip-offs might have stuck with a heavier weight bow and arrow. But I can shoot a 40# bow all day, whereas my shooting suffers by the end of the day with 45# or more. (Actually, my shooting suffers throughout the day regardless of what bow I'm shooting, but that's a different issue!)
My mentor, Rick Welch, shoots whatever bow he's currently hunting with, 55#, for example. But I'm not Rick Welch.
Sorry, can't help you with D shaped longbows, but I would imagine 45# would be sufficient.