Digital BW, The Print

When I looked at the MIS UT-7 page, I saw the following inks listed:

Eboni Black
(Cyan Position) Dark Black	
(Magenta Position) Cool Toner	
(Yellow Position) Sepia Toner
(Light Cyan Position) Light Gray	
(Light Magenat Position) Light Cool Toner	
(Light Black Position) Custom Light Black	

I see 3 that are denoted as "toners" (Cool, Sepia and Light Cool).  That 
leaves, I assume, 4 blacks used in neutral printing (Eboni Black, Dark Black, 
Light Gray and Custom Light Black)

I have 2 questions: (a) Are my assumptions above correct as to which inks are 
used for neutral printing?  (b) More fundamentally, if I am correct, I'm 
wondering how much of an improvement in quality one could expect to see 
for neutral grayscale printing with the 4 blacks described above, versus using 
a RIP with the Epson inks.  I don't know for sure what Epson inks ImagePrint 
uses for neutral grayscale, but I think I read somewhere that it's predominately 
black and light black, with smaller amounts of cyan and magenta to cool down 
the inherent warmth of the Epson blacks.  (I have no idea what inks 
QuadTone RIP uses or in what proportions).  Given that I don't have access to 
a UT-7 inkset, I guess I'm wondering what type of improvements in quality or 
just difference in appearance we'd be likely to see with the UT-7 inkset.  Is it a 
matter of smoother highlights, given that the Epson inkset doesn't include a 
highly diluted black?  Deeper blacks overall?  Better tonal transitions?

(Please keep in mind that I'm discounting the toners -- I'm only asking about 
neutral grayscale.  Also, I'm not asking about the relative longevity, although 
this is an issue, given that some have hypothesized that you may get uneven 
fading over time by using any color inks to produce grayscale).