I agree, Photoblack on matte papers results in poor D max. I have found this on most papers including Crane Museo (1), Lana, Magnani, Somerset Waterford and Awagami Inbi. These are IMHO among the worlds most beautiful papers, so as I need to print on gloss substrates like Pictorico High Gloss Film and various Lustres, and thus have Photoblack in the 9800 most of the time , I'm not really happy. I have spent a lot of time and ink trying to get over this, generally by putting down more ink. This works with some images but not if they have lots of shadow detail. Obviously dragging down the curve decreases shadow separation. Custom profiles do not do much either. Sometimes 2880 dpi helps. With monochrome, tweaks in Advanced B&W or in the Quad Tone RIP are useful.
Why PhotoBlack performs so well on the photo type papers and so poorly on matte and art papers I have not had a satisfactory answer to. Perhaps someone out there could explain it.
As a lot of the black in colour images comes from the denser cyan and magenta in the K3 inkset there might be a way around this . ImagePrint may be on the way but I'm not convinced. I'm also keeping an ear on the ground (are you there Bernard?) for news on Canon's large format 12 colour printers. If they arrive this year and they come up with a linear pigmented inkset, Epson will have to make a move in a similar direction and this will be a quantum leap. Ink prices may even drop. I'm probably excessively optimistic.
In any case my first roll of Museo Silver Rag is expected to clear Customs this week .
As soon as I have a profile and made some prints , I'll post my impressions.