I got to see one of their little tiny ceramic-bladed knives in a store. Hell of a sharp blade. I'll say that again. Hell of a sharp blade. Was it worth the 150$ (overpriced, I know) for a little 2" blade lockback, no.
I was looking pretty seriously at the Infinity, but since it has a liner lock, I somewhat lost interest. I like the looks of the delta a lot, but since it doesn't have a thumb stud or anything, I lost interest in that one too.
My feeling is that if you're going to be really nice to your knife, it's a decent investment. But a knife 'oops' could cost you your whole investment, whereas with a steel blade, your chances for recovery are much better.
My two cents.