I had trouble pointing my arm harness to a 6mm hauberk because the space between links was too small for a normal arming point to fit through without an annoying amount of effort. Also it was about 20% heavier than my 9mm hauberk because there's so much more metal per square inch. But I will say that maille was like wearing a suit of liquid iron. A friend once joked that the mesh was so tight even the mosquitoes couldn't penetrate it.
Incidentally I'm selling that hauberk if anyone is interested LoL!
Scott
Yes, the weave on it is substantially tighter compared to the 9mm. Extra weight, extra protection.
As Aiden said, post the hauberk up in the classifieds. I'm really tapped out, or I'd probably go for it.