Extended ACL Administration

We are a large company with offices worldwide. We want to restrict administration rights of the local administrators but enable them to do their jobs in their own area. We have tested extended ACL and found it that in theory it works well. Our problem is that we have a very large number of different OU1 as well as hundreds of groups, resources and mail-database documents. Does anyone have any ideas how we can change these 30,000 documents within a reasonable time? Is there perhaps an add-on tool we could use?