There are a lot of folks that get spun up by these differences in nomenclature. When I was a MEU assistant Air-O, we had CWOs, no-shit gunners, Master Sergeants, and Gunnys that would get really bent about this. When we were with the army in Kuwait, the army guys would call over asking for "Chief Benotz" (meaning Chief Warrant Officer Benotz), "Sergeant Schmuckatelli" (meaning Gunnery Sergeant Schmucketelli) and the like. I myself got blasted for calling a Master Sergeant "Top", which is quite common and accepted in the air wing. Some of them don't like it. Also, it's common (though not technically correct) to call CWOs in the airwing "Gunner". At the same time, many grunts will call a Captain "skipper", which I always found odd. I understand why they do it (Company Commanders), but it just seemed a little odd from my perspective.
The best bet is to always go formal (Chief Warrant Officer, Master Gunnerery Sergeant, etc) until either they tell you it's cool to call them something else, or you see enough other people equal to you (in terms of rank, experience, and familiarity) call them something different. If you go formal, the worst thing people will think is that you're a little stuffy. Better that than causing a scene or embarrasing yourself.