Digital BW, The Print

I use an Epson 860 (4-color 8.5" versions of the venerable 1160) with Lyson
Quad tones inks.   I print to glossy paper as my images are sent to litho
duplicators.  I've noticed that the Black & White prints done on my Epson
870 (6-color) have smoother tonality in the mid-high to high tones.  To be
specific, the 860 seems to have an abrupt shift in this area, making very
light tones appear as white areas because the ever so slightly darker tones
are missing, which the 870 doesn't do.   But the 870 has the "greenies"
because I'm using the Epson inks.

Epson is selling refurbished the 890 and the 960.  The 960 uses separate
tanks and has 2 pico drops, the 890 is the 2880 version of the 870.   Lyson
inks are available for the 890, not the 960.

I'd appreciate any thoughts on which would be the better choice to replace
my 860.   Or does anyone know how to get smoother tonality on the 4-color
860?

thanks to all

Rick Schiller
www.rickschiller.com