gsk -- Yes, the "holistic nature" of the "DIR System" exists -- but just because you can't get the whole enchilada doesn't mean you can't eat anything! Sometimes having some is better than having none.
For sure. I just see a lot of people spend serious $$ on diving gizmos they don't need and then are reluctant to spend <$300 for a decent BP/W solution. But yes, I think Primer should be opened to those in back-inflate BC's as well. Not sure how feasible it would be in a jacket-style BC with air pockets wrapping around the front....