We use the Dell TL4000 along with a Server 2008 R2 running on a PowerCault DL2200 box with 24TB of storage running CommVault Simpana 9. We use fiberchannel to connect the LTO5 tape library to the server at the moment, but by the end of the year it will be plugged into our fiber switches so we can do direct to SAN backups of our virtual clusters. There is definitly a learning curve around this software and after 2 months of reading, testing and trial and error, I am finally getting things to go my way. I plan on taking the CommVault classroom training locally starting next week, but it has really been a time consuming process to fully understand what the CommVault has been up to!
Having said that and after working with other solution like Symantec BackUp Exec and Roxio (formerly Dantz) Retrospect, I can definitly appreciate the flexability of CommVault Simpana 9. I would say figure out what you can afford to use, spend 25% more, and then fully utilize it and understand everything about it. Then, when disaster strikes, you can sit back and smile knowing that you just made saving the day really easy for yourself and that everyone will be happy. Not taking this seriously will give any protected data manager a pink slip overnight!