I have a dual P4000 NDMP/SCSI hybrid with Legato Networker on a
Solaris server.

The GigE NDMP drives appear as remote devices in Networker, I
assume Netbackup has something similiar.  In Networker, you
just add a device as 'rd=drive-hostname:/dev/nst0'. 

Jumbo frames are a must have.  We've had our unit for about a year,
but just upgraded the switch to one that supports jumbo frames.  Backup
speed went from 11MB/s without jumbo frames to 18MB/s with jumbo frames.

We've been generally happy with it.  All enterprise backup sw/hw solutions
suck, and this one doesn't suck to badly.

John