I have been to both.

Storage Symposium is good, but SHARE is much better for what you are looking
for.  I am one of the Deputy Project Officers at SHARE on the Distributed
Storage Project.  There were many sessions at SHARE on TSM in the
Distributed Storage Project.  The quality of the people to network on TSM is
excellent at SHARE.  I highly recommend an TSM Administrator to attend these
sessions.  The main advantage to SHARE is you can submit requirements to TSM
Development and get the vote of many people pulling for you.

Yes, I am a person that believes in SHARE.

Besides SHARE only costs about $900.  The Storage Symposium costs a lot
more.  The reason, SHARE is a non-profit users group formed in the 1950s and
very well off.  Storage Symposium is an IBM Learning for profit offering.
If you have an Education Ticket from IBM, then going to the Storage
Symposium is basically free, but the ticket costs over $4K.