Symantec Appliance or Data Domain or HP-Store Once?

I'm currently using Data Domain 860; replicating out to two Data Domain 670 appliances.

The data feeding this is done from Symantec NetBackup v7.5.0.5 and 95% virtualized on VMWare; running on HP-P9500 and EMC-VMAXe SAN's (Both 8GB).

I can choose from the following choices; what's the pro/cons?

Symantec Appliance:  5330 and/or 5220

Data Domain 7200

HP-Store Once 6900 or 4500