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.
The actual support personnel and the support provided is very good, and they are typically very responsive to any request that come in. We have never had a bad support experience. All support has been based in America and have always been able to resolve any issues or problems that have come up. the automated call home feature works well.
Cost effective and performance were the main reasons why we took Quantum DXi. Software and cloud solution may be better for us right now. We are going to find some new ways to do backup and DR properly.
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.