They are mono-charged. The 5000 is a twin tube and the 9000 is a tri tube design. Not real sure where your going with the tube design discussion, as it still does not change the result in ride quality after testing.
What I was referring to is that of course a mono-tube shock is going to ride/respond better on a beat out road or wash boarded dirt road and etc than a twin tube. The insides are totally different in design. So if you took and compared a bilstein 5100 to the Rancho 5000 then the bilstein will out perform every time, but that doesn't mean Rancho sucks. See what I am saying? And on highway driving you cant compare the same two and say the brand Bilstein sucks because its too harsh. Got to make sure you are getting shocks that fit the intended use.
I have no doubt in your results that the 5000 and 9000 didn't ride or rebound like the others you tested, I just felt like if the OP may want to try the 7000s it might fit his wants/needs if you haven't tried them. May be the worst or best mono tube shock for under $150 :shrug: ..