Cordovan is unquestionably tougher and more wear resistant than calf. The thing that has to be kept in mind is pretty much what jaywhyy just said. The number of recraftings that a Goodyear-welted shoe can take (no matter what it's made of) is limited. Every time the welt is removed and a new one is stitched on, the leather upper at the inseam becomes weaker and weaker. Think of it like tearing a solid piece of paper vs. a piece with a perforated line. The more perforations, the easier it is to tear. When they stitch on a new welt, the needle is just "machine gunning" through the leather, and it is undoubtedly making new holes and widening others. After this has been done a few times, it simply becomes too weak to keep being done.