Part of the problem with cordovan is that the name has been around so long that it has taken on additional meaning. That is, it's not just a tanning proces from Cordova Spain, it's now also a color. Kinda like Coke went from being a brand to being a flavor.
I'm not sure if I've ever owned a tab made with the stuff from Spain or not but I've been using either the basic Neet cordovan tab or another one (can't remember the brand) with a small rubber spacer and an elastic finger loop ever since I started. I have an old Neet tab that is as slick as glass, has no crease and has shot thousands upon thousands of arrows. I think the longer you shoot them, the better they get.
I have noticed though that when I have the chance to handle before I buy it pays to check each one to see how slick it is. Some of them feel softer but not as slick (more like regular leather) and some of them are real slick and feel almost like plastic. The slick ones seem to be the ones to get.
It's also a "buyer beware" thing. Due to the confusion about color vs. tanning process some cordovan is not REALLY cordovan. I once even asked an archery dealer if he had cordovan tabs and his answer was "I can make any tab cordovan with a bottle of dye". Thing was, he wasn't trying to rip me off or be a jerk, he honestly thought that cordovan was just the color.