Sorry to be so late in responding, but just got to the point of reading this section.
I have worked for 2 global companies that were OEMs. Both used one location for document control and intranets to distribute. I firmly believe that is the best way to go.
In both companies - general procedures (Level 1 and Level 2) were almost 100% international - same procedure used at all sites. Then Level 3 and 4 were semi-unique to the processes, equipment, and even local languages spoken.
I'll name one of the companies: Acer. Most people don't know that Acer is one of the biggest computer manufacturers in the world - but they build a lot of computers for other companies and put their logos on them. They run all the plants in all the world from their main Doc. Control in Taiwan.
It works, if it is set up right.