Allen,
I see your point, finally, that BIGFS_AF will copy files, but BIGFS_GL will 
remove them.  Clearly, splitting the backup of one filesystem among multiple 
proxy nodes via include/exclude statements is futile. There are 4500+ 
directories under /ip, so virtualmountpoints aren't workable either. 

Andy, Skylar, Richard and Roger, 
You responses are full of good advice that will take me a few days to absorb 
and implement.  I am on a different track now than before.

With many thanks and best wishes,
Keith