Thought I'd just update this thread.

I went through a security scanner this week. I know the sensitivity on those things change from time-to-time but I got through with my Mephistos with no issues. I asked the security person to do me a favour and scan my shoes with her wand. (There was nobody else in line.) She did and the wand did go off.

So, it seems there's a small amount of metal but not enough to set off the scanner.