Logical and economical storage of image archive

I totally agree.  My archiving system is very simple:  everything is available instantly online on an individual 2TB in my system, and I have two external 2TB drives that I sync to it on a weekly basis (or more often if I have some special need).   One of the two external drives is stored offsite and I swap it with my onsite drive once a month.

My daily system incremental backups include any changes made to the archive drive since the last offsite swap, and I don't delete files or videos from my camera memory cards until those incremental backups have been run.  So I'll never loose any files if a hard drive crashes and if an unimaginable disaster should befall me the worst case is that I'll loose the last month's worth of files (which, in that kind of circumstance, will be the least of my worries).

The more complex you make your backup strategy the more likely it is to screw up.  KISS (Keep It Simple, Stupid) is the best policy, IMHO.