Dear God do they wear off. I had a gun metal Zmax for about a month and a half, it was half chrome, half gun metal, half copper. The gimping on my Benchmade knives wore it off super hard, scratched the crap out of it, made it just look awful. The Sigelei's do scratch like hell, so if you're not worried about that, it's not an issue.
The Zmax is a plated finish on a copper tube. Not a bad metal to have (dude ran one over with his car, three months later, it still works), but they wear off. Even the stainless, they wear off. The Sigelei's are CNC'd out of a block of stainless steel - much stronger, a little fatter, a little taller. Much sturdier. But they do scratch. A lot. I currently have a Sigelei in stainless, I love it.