Blue Board Drywall for the Whole Kitchen?

[Nathan Grubb]

I own a two flat where the upper apartment has a sloping ceiling in the kitchen. The person who owned the house previously (and apparently tried to flip it.....I think.....) used that very thin, plastic coated panel board for the ceiling. The heat and moisture that accumulate up there have already begun taking their toll on the paneling and I want to replace the whole ceiling with drywall.

Since the roof slopes over the sink and oven, I was planning to use blue board there for the moisture and fire resistance. I have heard multiple people on here talk about "remodeling up" to nicer quality items, and I was just wondering if it would be worth the investment to do the whole kitchen with the blue board.

Is it worth the extra expense, or should I just use regular 5/8 drywall for the other sections of the kitchen ceiling?