Re the benefits of tapes, I suppose it depends on your setting.
If network bandwidth is too expensive, tapes plus sneakernet makes a cheap, high-bandwidth network technology to get your backups off-site. If network bandwidth is available and cheaper than the manpower, I'll run rsync over ssh, thankee; manpower is the one part of computer systems and their support that refuses to get cheaper.
As for security, I regard that as an orthogonal question. Systems have to be secured, backups doubly so. If you don't have the backup system adequately secured, your backups can't be trusted. Even if they're spun onto tapes later. And _lots_ of people don't remove those tapes, witness the popularity of the really gigantic tape jukeboxes intended to make for no-human-intervention backup systems.
If your backup server is adequately secured, I'd generally rather just pile it up with enough disks, rather than messing with tapes.
-Bennett