For some of us, NDMP really is a good choice. We configured an accelerator node, attached via FC to an LTO tape library. We rely on 30 days snapshots for day-to-day user file recovery, then run weekly and monthly fulls to tape. This has been an extremely cost-effective solution for us, and still meets our operational goals.
The only thing that would increase our solution would be to purchase a partner cluster, configure it to keep 60 days of snapshots and replicate to it via SyncIQ. At that point, I would probably move my tape library to a third location, and backup the replication target to tape. That way, I have instant recovery from local snapshots, longer-term recovery from the DR cluster, then archival recovery from geographically-distant tapes.
Full disclosure: I'm a fan of the NDMP protocol, regardless of it's inability to restore across vendor solutions. I manage several NAS products, some from multiple vendors, and NDMP lets me share resources (tape) where I need it. We've been able to provide three-way NDMP backups and restores for other organizations on Campus, who didn't have much experience with NDMP.