I must have missed the reference to the Birchline series, but here are the specs from drbasscabs.com:
BL 2128/2124 - 60 pounds
BL 2124 (Neo) - 51 pounds
And the MDF version:
Rx 212 - 52 pounds
So they're a little heavier than you mentioned, even with the neodymium magnets. Although one of the Rx cabs loaded with neo speakers could be an impressively lightweight 212.
I'm very curious about the spray coating - it seems like that would be MUCH more durable and easy to clean than most cab coverings. EC offers Naugahyde in just about any color you can imagine, which was a plus for me. I'm sure it's not as durable as the spray coating from DB, though.
I'm intrigued by the 12/6/tweeter cabinet of yours, Bill, and I'm thinking it would make a great standalone for practice or smaller gigs. If my financial resources were a little greener, I'd look into getting a couple DB cabs to do a direct comparison with EC. Maybe if someone from the NY/New England area has DB cabs, we can set up an experimentation session some time.
Another thought on the small shops: Although they may not carry inventory like a major manufacturer, they can sometimes do things to help the buyer that a major manufacturer won't do. When I spec'd my 210 to match my 212, Tim started the construction right away, and a totally customized cab was ready to ship by the time I gathered the money for it. I doubt many major manufacturers would start building something custom without seeing a penny from the buyer first. It goes both ways with the smaller companies.
And certainly, like Kevin and Bill said, to each his own. There are just as many options out there as there are ideas in your head.