Playing the devil's advocate here, the flaking that you're experiencing will happen with all Neodymium Iron Boron magnets with nickel platting. The underlying metals are highly brittle, which means that continuous clacking together will eventually break off small pieces of the NdFeB under the nickel coating. This metal sand will no longer support the shape of the original coating, leading to warping, weakening, and eventually flaking of the nickel coating. The only thing that really determines the endurance is the depth of the coating, and Zen makes no claims that the depth of their coating is better (only that it's more shiny and possibly more uniform).
As a disclaimer, I have not owned either zen or buckyball's magnets (although it's very possible that I've gotten magnets from the same supplier). I'm just a fan of the NdFeB magnets and have a moderate-large amount of experience with them.