According to speedplay they're not cross compatible:
"Can I use Light Action cleats or X Cleats with my Zero pedals?
No. Light Action cleats and X cleats cannot be used with Zero pedals, and Zero cleats cannot be used with Light Action or X pedals. Only use Zero cleats with Zero pedals."
Now that could be a manufacturer being overly conservative.
If I could use Zero cleats on pedals, I'd definitely give the Zeros a try. Buying one set of Zeros is one thing, buying 4 is another.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.