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.