Digital BW, The Print

Actually it's a good question. I tried to measure the difference between BO mode that prints with one black color and EB6 which prints with 6 colors.
 If you look at high resolution scans of 21-step wedge print  you'll see it as combination of white and gray spots. I tried to calculate the size of the area of all white spots and their brightness, the same I did for the gray spots. To do this I've used Photoshop's analyze tool on a cropped 1" each side rectangular. Then I calculated:
roughness = (white area size * white area RGB)/(gray area size * gray area RGB)

So I've got numbers showing how much of whites we have relative to gray.
Here are some numbers for 50% step on the 21-step wedge printed with different combinations of BO and EB6:

0%BO:100EB6  - 0.12
20%BO:80%EB6 - 0.18
40%BO:60%EB6 - 0.27
60%BO:40%EB6 - 0.3
80%BO:20%EB6 - 0.49
100%BO:0%EB6 - 0.54

The bigger the number - the rougher the ink. As you see 100%BO is 4 times less smooth than EB6. I didn't measure for UT14 but my guess it would be in the middle between BO and EB6.

Now the next question is: how rough ink should be to so the roughness would become visible for the viewer? 
I don't have answer to that, to my eyes the print made with BO looks the same quality as EB6 (sure EB6 is warmer, BO whites are whiter).
I'm using 1400, Paul mentioned that on 1800 BO prints had some banding. 

It is possible that large prints will have noise more visible with rougher ink.

It looks to me that the combination of BO and EB6 I've recommended in my article http://photo3dart.com/wordpress/?p=370 gives the best compromise between coolness of BO and smoothness of EB6.

Still I think that difference in quality between BO and EB6 is very small, between UT14 and EB6 it's even smaller.

Actually UT14 is a different ball game - it introduces colorants, so here we have to consider compromise between image tone and longevity. 
If you are worried about UT14 smoothness you can replace GLOP ink on Y position with EB6 Y ink (as Paul once recommended) and get smoothness close to EB6, if you want to print on glossy paper you can always put GLOP back.

If somebody is interested in details of measuring smoothness of the ink please let me know and I will publish it.

Jacob Mann
http://www.photo3dart.com