Finally found the thread the first link cites here
OM606 fuel supply issues
From my reading, I have come across very few 606 owners who have no (0) bubbles in the fuel lines. Most accounts I've read here mention some or very small bubbles but still they are present in the system. I've read less than a handful of accounts that mention a larger diameter supply line with sucess at getting rid of them. Now that seems like a simply elegant solution this forum is known for, right.
Perhaps one of the members with a fluid dynamics background could chime in with thoughts.