I too have had good experiences with Ampersand Pastel Board, although these days I prefer to buy their gessoed panels and paint on one or two coats of Colourfix pastel primer myself. I like to utilize the brush strokes from laying down the primer myself in the finished painting, and find that pastel board has too uniform a surface for my taste.
Like Bluefish I have framed these boards with out mats (although I usually varnish my pastels with acrylic varnish) using spacers and glass....
I particularly like the small gessoed squares for small work, and these look great framed without mats.
Good luck, and let us know how you get on.