Anyone used the Cobalt string series from Ernie Ball?
Are they any good, different from the regular slinky?

Increased sustain, clarity and output?
Resist sweat and moisture?

All I remember is SpaseMoonkey saying that they snapped more often, there was a thread about it.

No, I haven't but I found this thread at Ernie ball forum about it:

http://forums.ernieball.com/ernie-ball-str...lt-strings.html

Very first set I put on my guitar the low E unwound. I was pretty steamed to say the least after spending $10 on them, I currently have all my guitars with them now. I honestly don't feel or hear any difference tone wise. But I'm sure massive gain doesn't help that at all.

Ernie Balls have never been good to me tho. Its the only strings I've ever had unwind/break on me.