First and foremost, the support for arcserv is lousy at best - and trust me
you need support. CA has long been known for disappearing after the contract
is signed. When we finally got to the point where we demanded that CA come
on-site to get the product working three things happened: 
1. We found out that everything was installed correctly.
2. It took their own engineers several days to figure out how to install the
fixes they recommended.
3. A considerable amount of data (months) was lost.
Tape management is more difficult, and less efficient, and not automated.
No incremental forever.
Very limited versioning and retention capabilities.
Is the support for Tivoli any better? Maybe, maybe not. The thing is I have
needed very little support since it was brought up, and the procedures for
updating the code are fairly intuitive. 
Need more?

Cory