Lots of Backup Exec customers do that so not really an issue (as long as file server is NOT virtualized, see below*):
- No need for a second set of server hardware (with associated racking costs)
- Gain against use of network (LAN) bandwidth (depending on device being backed up to)
- Slightly more complicated DR process in the event of complete failure of your file server
- Memory and CPU usage will be higher (mainly during backup/resore operations) - Requirements for CPU and RAM are a lot higher if deduplication is in use.
*Backup Exec can run a virtual server but cannot write to physical tape (using passthrough technologies) which slightly reduces the options for where you are backing up to if the Backup Exec Server is virtualized. I belive you will also be limited against using our virtual agent backup technology (which has some major benefits when it comes to DR resores of VMs)