I once tested (backyard) a regular cowhide, a sharkskin, and a cordovan tab in the same design. The release was very smooth with the cordovan, fair with the cowhide, and not so good with the sharkskin. In fact, at about 20 yards, the arrow would impact 6 inches differently between the sharkskin, and the cordovan. I switched back several times always with the same results.
The cordovan is slicker then sharkskin, but I never could explain why there was that much difference in where the arrow impacted. That's one of those things that I want to revisit.