Digital BW, The Print

I'm wondering about the use of the ABW Mode and what advantages it 
provides over a regular ICM flow using the supplied Epson paper 
profiles or custom profiles.  The latter, of course, allows a soft 
proof mode in PS, which the ABW (to my knowledge) does not.   I realize 
that the ABW mode allows toning, but other than that does it offer 
something?  I had understood earlier on that ABW provided special 
dithering and a minimal use of color inks.  I have printed both ways 
(but only on matte papers with MK), however, and I can see no 
difference in dithering, ink usage or appearance of the prints.  I have 
examined the prints by eye and with a 7-35X zoom microscope and I 
believe they are identical, the ICM prints very closely matching the 
ABW "Neutral/Normal" (not "Neutral/Darker") prints.  Both work flows 
are providing excellent prints, but ICM system provides a better screen 
preview.  

Any comments or thoughts on this would be *much* appreciated.

Walt