I can't really say which is better. I do have one of the old DC over the counter blocks. I pulled it out of the original shipping box (drop shipped) from Keith Black Racing Engines. The block has the WT stamp and that is pretty much it. It was also sold as a "racer special" probably for the Super Stock guys who could run a .020 over bore max (I think those were the rules back then, please correct me if I'm wrong) Anyway the block is rough bored around .015" to allow the racer to finish bore as needed. A warranty block, from back then, would probably be a standard bore.
I have no experience with the new stuff but thought I would pass this on for the old stuff that is still out there.
Jim