I forgot to mention earlier that the Epson hot press sheet papers I've had, and Exhibition Fiber sheets for that matter, have always been very flat. Flatness is one reason I use sheet paper whenever possible - including the 24"x30" size EEF sheets. It'd be pretty disturbing to have to use a D-roller on these. FWIW, I got a D-roller to uncurl prints on roll paper and it does not work well on anything but cotton rag papers, which don't hold such a stiff curl in the first place. On alpha cellulose papers (like EEF and Ilford GFS) the D-roller leaves its own permanent "wave" in the paper at intervals equal to its circumference, apparently from the leading edge of the sheet. I think it's because the diameter of the D-roller is way too small. These waves aren't severe, but in alpha cellulose they are permanent. I think the structure of the paper is crushed or damaged. If you're only dong the leading edge and not making a full 360 degree wrap, it's probably fine.
I agree about the D roller. It left waves in some large prints that I had made on Canson Baryta Photographique. That paper is quite stiff and has a lot of curl.