Good practice is to leave in good terms, secure a No Objection Letter from your present employer and at the same time contact the new HR office in order to clarify whether there is any objection at all. In a well informed HR they must know
about given the contacts they have in these places.
6 months ban used to be the ban (and probably still is), but I also got other the opposite. I remember reading sometime ago an article in the Gulf News. During the weekend they have a kind of an adviser that addresses labour issues.
I know of guys going to other Emirates without having any 6 month ban. Good luck!