I also work for a smaller company and I have 2 Drobos in service for backups. They are working fine but you are limited to USB 2.0 speed. This is true when you use the associated DroboShare network appliance as the connection from the Droboshare to the Drobo is USB. BackupExec does not like the DroboShare so I have them directly connected to a server. This arrangement keeps us from running all that data across the network as well. The only downside to the Drobo (this is unsubstantiated as I have not tested it) is they are supposed to be susceptable to data loss resulting from loss of power. If you are operating a data center with adequate UPS and a backup generator this would not apply. 4TB of redundant SAN for less than 1K is hard to beat, we'll see how long they last.

In all seriousness, it is perfectly ok to say no to the suits. I have found that saying "NO we won't do that and here's why" followed by a dumbed down explanation that is understandable given the individuals level of expertise or lack thereof, not only works but adds to your credibility. Also if the reason is budgetary don't be afraid to say so, you might end up with a few more shekels in your IT budget. "I told you so's" are also ok if done tactfully. Good Luck