... I am beginning to wonder if I should just stick with CR2s to help manage the spirraling number of external HDDs required.
DNG was designed to ensure that years from you'll have a means of support for your archived photos. What if Canon, for instance, many years from now, changes the specs of it's RAW format, or is bought out by a competitor and lose support for backwards compatibility? It can happen. I have boxes full of obsolete backup tapes, zip disks and other forms of media. Formats are just as vunerable.
You could suddently find yourself in situation of having to redo everything to salvage or maintain the archive.
DNG also allows you to accept media from several sources and formats, and convert them into one. Likewise, you can be sure your edits (hard work) will be included in the DNGs when you hand them off to others (i.e. the designers and non-photographers whom will use the images for brochures, etc.).
DNG allows you more choices as third parties, whom write better code and software, give you more options or choices to work with your files.
This is not a pipe dream, I'm witness to the above in my everyday work.
I'm talking workflow here. Archival is a different beast (regardless of your format). The only fix that pays off for archival is diligence. That means upgrading your archive and moving the files off to the current technology. Drives fail and optical disks corrode over time. Time is the enemy.
The thing about archival and memory requirements is that you have to brutally honest with yourself when grading and choosing which images make it that far. If you keep absolutely everything... you get the point.
The thing about a workflow is that you need to create one... Then stick with it. If you change, then it'll be a ripple effect with your past images and you'll make more work for yourself.
Form follows function. When I shoot, I'm concerned only with getting the shot. Edit comes later. When I collect and grade images, I'm only concerned with keeping the best and dumping the rest. Only then do I concern myself with the naming the files and editing. Once edited and the client accepts. My only concern is to get them off the machine and out of my way.
I'm ok with thumb nails in a database. It's not different than portfolio or cumulus. These applications may tell me what disk I need to insert. But if I include the location in the metadata, then a simple search will tell me. Drive 1, 2, 3, disk 1,2,3.. etc.
I think even Michael (correct me if I wrong), with all the images he has is about twenty drives or so. Heck I have about 50 drives that covers about five years of video work alone. However, those are corporate projects that rarely last a few years and are redone from scratch anyway. A drive with a shelf life of three years is sufficient for that. The new sata's are warranted for five years, but an unspun drive will actually corrode or stop working after two years. So, once a year I spend a day spinning them up and running check disk. Those that reach their third year are replaced with a new (pending what they hold).
Images are forever yes, but it's easy to mark the date on the drive and put a note in your outlook calendar to remind yourself to check and replace that disk or drive.
I didn't mean to write a book here. I've flung enough mud.. hopefully some it will stick.