Ebay spot check on a couple of recently sold delta brakes.
Complete NOS NIB 5th generation brakeset. Sold for USD $1625 on 3 Dec 2009.
1st generation calipers in very good condition (well there's a somewhat large gap at the top of the front caliper faceplate...) but missing one quick release. Sold for $1238 on 24 Nov 09.
Certainly the 1st gen brakes are far more rare and, to me at least, far prettier. Even with the differences in lighting it is still evident that the 1st gen brakes have a warmer satin sheen and a more curvaceous body. Yeah, they didn't work real well and could fail catastrophically but that's just a minor detail... Not having the other QR appears to have affected the sale price. Either that or someone really wanted the 5th gens.