The drywall installers ran short of cement board, so they used a small piece of mold resistant drywall at the top of the wall where the shower head is located (see upper right of first picture). I brought this to the attention of the contractor, but before they replaced the drywall with cement board, the first two layers of mud and tape were installed (see second picture). Our plan is to tile the walls in the bath tub/shower surround all the way to the ceiling. However, the ceiling will not be tiled.
At this point, is it better to have the drywall replaced with cement board, or just tile over the mold resistant drywall? The contractor has assured me that they can cut out the drywall and slip in a piece of cement board under the vertical corner bead running from ceiling to floor on the right and then install new tape and mud for the horizontal seem between the wall and ceiling.
In case it matters, the drywall installers are using ProForm Lite Blue Joint Compound, a "vinyl base ready mix lightweight joint compound."