I just spent some time working with some gampi (95 g) dmax was poor (and the very warm tone to the paper didn't help either), but with some images the tonality was beautiful. Some issues with the paper de-laminating in small areas, exposing the underlayer. I used the Richeson brush, but the developing time needed to be about double what I need for Platine. I've just received a couple of sheets of 30g stuff, and have ordered some fumed alumina from Bostick & Sullivan which has shown some promise in getting more convincing blacks.
Thanks for the view camera link - using a sheet of mylar during the developing, clearing and washing process is a good tip.