I have a mounting press that I regularly use to flatten prints. About the only prints I ever dry mount are platinum/palladium when I print on vellum. I like the look and color these prints have but the vellum just never stays flat without mounting it. I normally mount it to either Weston Diploma (I think that is what it is called) or to Fabriano. I have had no problems. Looking at the back, I can tell that there is something mounted to the lighter weight Weston paper but not on the Fabriano.

I have not tried it but I think you might get some surface effects if you mount to a paper with a pronounced texture.

Dan