Digital BW, The Print

I recently purchased an Epson Stylus Photo 1280 printer and a set of UT2 inks.  Prior to 
this setup, I had been using an Epson Stylus Photo 870 with Lyson QuadBlack inks, and 
only very recently did I try the MIS Quadtone Variable Mix ink set with the 870.

The results from the Lyson inks were acceptable, but not quite "just exactly perfect." 
That's another story, as my question is really about the UT2 inks.

In the prints I've made with the UT2 inks, I've noticed, under a loupe and with the naked 
eye, obvious dot patterns in the highlights, similar to what one would expect when 
printing with black only.  The QVM and Lyson inks, on the other hand, do not show such a 
dot pattern in the highlights.

Is this normal for the UT2 inks?  I've printed stepwedges, and the dot pattern is quite 
visible in the 90% step and above.

In comparing the individual inks used in QVM and UT2, I believe I have an explanation:  it 
appears that UT2 does not have a light gray (toned or untoned) ink as QVM does.  No light 
gray would imply that the highlights in UT2 are made up of a darker gray, which would 
further imply that widely spaced dots would need to be used to make up for this.

Does this make sense?  I'm new to MIS inks and using Paul Roark's curves, so I'm willing to 
believe I am not doing something right; however.  I even printed with QuadToneRIP, but 
the results were the same.

And yes, I've checked that the print head is not clogged, and that I'm selecting "color" and 
not "black" in the Epson driver.  The 1280 is brand new, and has never even had a color 
cartridge in it-- I've been using the UT2 cartridges from the start.  Printing the MIS purge 
pattern shows that all inks are printing normally.

I would appreciate any comments or suggestions.  I've been lurking in this forum for a 
while, and the depth and breadth of knowledge here is fantastic.

Thanks,
Steve