I have never specified paper-faced gypsum sheathing since 1986. Once I understood the benefits of fiberglass facing and siliconized core. There was no doubt for me.
I’ve had difficulty with using fiberglass faced gypsum board and the interior. The fiberglass surface is not as smooth as paper and getting a paint system that will look like the finish on a paper-faced gypsum board has no “support” from either the gypsum manufacturer or the paint manufacturer.
Same issues as Ed mentions. We spec the mold and mildew resistant boards such as National Gypsum’s XP Board for wet areas and for areas finished prior to enclosure. Clients have complained about the appearance of fiberglass mat-faced board on the interior when receiving paint but no skim coat.
I agree with Phil. The only way I’ve seen to get a satisfactory painted finish with glass mat faced gypsum board is to specify a skim coat of joint compound over the entire surface - in short, a Level 5 finish according to ASTM C840, GA-216, and GA 214. $$$ Of course, a skim coat is not necessary if the glass mat faced gypsum board is a substrate for a panel product.