I've used a Pro100 for the last ten months, almost exclusively with Red River papers. My favorites: Pecos Gloss, Polar Pearl Metallic, and (for b/w) Aurora Natural and San Gabriel SemiGloss Fiber Baryta. I have not compared between paper brands. Overall, I'm happy with the Pro100.
Regarding ink usage: in my experience, printing consumes about 65% of the ink, while maintenance consumes the remainder. Since I do not print daily, by maintenance, I mean the printer's normal routine of cleaning ink heads after several days without use. This seems to happen every time I turn on my printer, which is about once or twice a week. (I plan to start turning it on daily, as part of my computer start-up routine, to see if this lowers ink consumption for maintenance.)
YMMV,
Bob
PS: Off topic for sure, but does anyone know of CD/DVD disk printing software for the Pro100? I've used the software bundled with the printer, but it is quite limited in what you can design.