In our environment, we're using Exagrid [EX Series] on Remote/smaller sites, with something around 50TB of data (to be protected) and it works really well. I see no reason for it to work on larger scales, it is very scalable, you can natively replicate backup data between Exagrid appliances (like in a Prod/DR scenario). So, it should work fine on larger environments also.
Lower cost of implementation versus scalability. In addition to promoting a perfect interface with Veem, which has become the company's backup tool. We also had the opportunity with Exagrid [EX Series] to have a global maintenance contract, which meant a reduction in support expenses.
Symantec NetBackup Appliance is much better than any other backup solutions out in the market, with new features like Oracle Intelligent Policy and extensive support for virtualization.