The only knives with black blades I've got are those that I just couldn't find with satin finished blades, down here in Argentina we don't have too much to choose from. So far, the worst coating in terms of wear resistence has been Cold Steel's teflon coating. The good thing is that it's easily removed. Whatever ZT uses seems to work fine, my 0300 and 0350 have been through hell and look just fine (the colour of the coating has dulled a bit and there are tiny scratches that you need to pay very close attention to see).
Sorry for the crappy pics, cameras and I don't get along well.
The wear on the Ka-Bar and the RAT-3 is from batoning, shouldn't be a problem with a folder.
This Microtech gets regular use. The blade coating is fine, but the anodizing on the handle is wearing off in some small areas (I don't really care).
I'm sorry I don't have a more detailed photo. The American Lawman and the old Recon 1 in this picture had Cold Steel's crappy teflon coating. It wore off quickly, just from rubbing with stuff in my pockets. I took it off of the AL, the good thing about it is that it's very easy to remove.
These two ZTs have been in my EDC rotation for a couple of years, the 0350 gets the most use. The coating is holding up quite well.