There's a lot of varying opinions on this.
Most deck clips will keep your cards nice and flat - at the expense of damaging the boxes the cards are kept in, especially in terms of flattening embossing/debossing on the tuck box. If you ditch the ad cards, jokers or both from your deck, the damage is even worse to the box because there's less inside the box to support the box's structure.
Then there's always that "Gee, those cards are in a fancy clip - WITCH!!!! WITCH!!!!" factor. Same thing applies with pack jackets - it's an accessory that mere mortals have never heard of, so immediately the deck that came out of it becomes at least a little suspect in the minds of some spectators.
I own the Blaine clip you got rid of, remember? I use them (I had a brown one before I bought your black one), they're holding up fine. No special treatment to the leather. Albeit I don't use them daily, I do carry decks in my back pockets at times and use the clips to keep them from warping.
Porper's clips are the best design in terms of flattening your cards. Most of the rest don't supply adequate pressure.
Carbon fiber clips are THE BOMB. I saw the CARC version and it's not just bloody gorgeous, but it's incredibly lightweight while still being strong as hell. The one and only drawback I can see with them is that while metal - even Porper's aluminum - can be bent a bit with strong hands or weaker hands with tools to accommodate thicker decks, I don't think the carbon fiber ones would fare as well, as they're more prone to cracking than bending (though that is entirely an educated guess and not actual tested fact, so treat is as such).
I couldn't speak for the abalone - frankly, all those exotic coverings sound like luxury extras rather than standard features or even options. They don't improve the performance of the clip - they just look pretty. Some people buy economy cars that get the job done while some people get SUVs and still others get high-end performance vehicles. Different strokes. Try to argue that the racers are better, and I'll agree - up to the point that things like gas mileage and cabin/cargo space get mentioned as yardsticks against which to measure them...
Cow leather is nice, simple, low maintenance and matches your wallet. Any other exotic covering is mentioned and I start to think you're just looking to show off!