Rick,
I am just getting started with FILE deviceclass storage pools, so take the 
following with ample grains of salt. However, my experience contradicts 
swg21497567. Or, I might misunderstand that Technote. 

This is a TSM 6.2 RHEL5 server. The file deviceclass has fourteen 2 TB 
filesystems on raid10 ldevs.  Volumes were predefined to the storage pool with 
'wait=yes', so they were created one at a time in round-robin order across the 
filesystems.  

A small amount of client backups are being written to the file pool at this 
time, so it is clear how volumes are being used.  Client backup files are 
written to the storage pool in volume name order, not in filesystem name sort 
order.   Today I see one full volume in each directory, and many empty volumes. 
 If the Technote applied, all full volumes would be in the first directory.

Ås far as I know,
Keith