Currently in BE12.5, there is no integration with PureDisk. No Export to tape, that is reserved for NetBackup.
There will be some in BE2010, but it's still pretty cloudy exactly what that will be.
Although note, BE2010 has a PureDisk lite ported into it, so Dedupe will be native to BackupExec later this month. You would use PureDisk when you need more scalability above the 16TB's that BE will support.