WoW, I already read through a lot of Building Science website. Amazing stuff! But I had a hard time finding info on solid-wood walls. And a lot of their stuff is pro-sprayed foam, for obvious reasons, but a path I would still like to avoid... I'll check the links a little later.
Thank you both for your input and clarification. Much appreciated. I may actually mix techniques... Use all rigid for a stairwell and bathroom for example (where I'm tighter for room and there are no plugs) and hybrid for the rest.