I've got to admit, I had real doubts when I read this, but here goes. I have a #8 block smooth bottom and a #8 slant with heat ring.
#8 slant with heat ring = 63.40 oz.
#8 large block smooth = 56.95 oz.
Thats 6.45 oz difference. We can blame some on the heat ring itself, but not that much I would think.
Soooo, at least with the examples I have, the older skillet does out weigh the later one.