I used “Alternative Drywall” and they did an excellent job.
I specified 5/8-inch Type X board as one wall was required to have a 1-hour fire rating. To keep things simple the drywaller used this material throughout. The contractor used Certainteed.

The wall behind the wall-hung toilet cannot be drywall; instead it needs to be cement board. The contractor used National Gypsum PermaBase 5/8-inch for this.
I was unable to source 5/8 Permabase a month later when I went to start on the shower construction. The only thickness available to a consumer like myself was 1/2-inch. So I used a combination of DuRock 5/8-inch and PermaBase 1/2-inch for the rest of the bathroom.
Permabase 1/2-inch is available from Florida Tile in NW Portland. They won’t sell direct to a home owner so I purchased through Campbell’s Tile Concepts.
Durock 5/8-inch is available from GTS Interior Supply also in NW Portland and they will sell direct.

Drywall Installation

They completed the job by spray-painting with a primer coat.