Damascus is goat hide, it's used a lot, and it seems to work well in a glove. It may not be as good as cordovan in a tab, but probably isn't bad. We may have to check that out.
Cordovan involves a lot of processing to get it so slick and durable. The cost of it is high and you may wait a long time. It was about 3-4 months wait the last time I ordered it. You may pay over $100 for a shell that will only make 12-15 tabs. That come out to about $7.00-8.00 per tab, not counting the cost of constrution, etc. A dealer has to struggle to keep their price down, but yet make a small profit.