Digital BW, The Print

> How exactly does it address the "B&W printing on the 2200" issue ?

It prints using mainly the two blacks and cools down the print with
small amounts og magenta and cyan. The result is a very neutral print
with minimal color shifts and metamerism.
 
> Did I hear that it allows use of the 2 black ink cartridges (including
> the "Light Black") ?  And this looks somewhat sepia-toned, right ?

That's also a possibility. If you select 'Gray gamma 1.8' or a similar
grayscale profile as the output profile when printing from photoshop
it will use only the two blacks. That will look like a sepia-toned image.

If you use 'Postscript color management' it will print with all of the
inks except yellow of which it uses very little or none at all. At
least I can't see any yellow with my 8x loupe.

> Does it allow 7-color B&W prints with less metamerism than the stock
> Epson driver ?

Yes. There is much less metamerism than with the Epson driver. I can't
see any metamerism at all, Matthew reported that he saw a little, but
nowhere near that of the epson driver. When I hold two prints out the
window in daylight the Epson print looks like it was painted green,
while the PowerRIP print still looks fairly neutral to my eyes. If you
decide to try it out I would be very interested to hear about your
perception on this.

Remember to print at 2880 dpi. It will be really slow, but unlike the
Epson driver there is a big difference in quality.