I'm not really sure how to gauge imps in the New 52 as of now. Granted Mxy has already pulled a full-fledged universe from his derby hat, just for the lulz-- but I've been getting the sense that all imps (namely Vynd) may not be on that level. Hopefully he'll display some quantifiable feats in the near future.
At any rate, I agree that he *should* win by virtue of existing on a plane of actuality well above that which Volthoom operates in.