Hello,
If you already have a large library that you would like to share may be 
ACLS may be suitable, especially, in Mixed environment where you may have 
Main Frame, Unix, large & diverse  backup environment.
Today, other options exists such as Library partitioning, VTL , disk 
backups etc to achieve the similar results, however, if you already have 
acls environment and want to utilize the benefits of it, may be worth a 
look, personally, excepts for better tape management  ( could get rid of 
DDS) i don't know if i would like to put all my eggs in one  basket.
Altimately, it may come down to cost and compatibility as typical MF 
environment may be running on 9840 tapes and you may not have the same 
capability available ( related to hardware) @ offsite dr.( There are 
always exceptions )
Thanks

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