Thanks for the replies. I recognize the limitations of the Pro100, but as was said, it is a quite able printer at its price point. (One day when I actually start selling my work, I'll invest in a better printer, but not now.)
RE: Platine and gatorboard. I use gatorboard for most of my mounting these days, as it is much cheaper than framing and stiffer than foamboard. Yes, you can have problems when cutting Platine mounted on gatorboard, but from my experience this can largely be avoided by using fresh blades, keeping the angle of cut quite low (get the knife handle close to the surface), and avoiding cutting in conditions of high humidity.
I plan to purchase a pack of Baryta Photographique soon and give it a spin.
Thanks again for your help and advice.
Bob