Digital BW, The Print

I'll try again asking this to you ink and printer experts.
Sorry to be repetative this is an issue that is haunting me and I think someone 
out there may know the answer. Paul?:

I have one final question before getting back to work. Why in the world if the
yellow channel is the PRIMARY ( though certainly not total) change in the 
Epson pigment inkset from Archival CF to UltraChrome, is it not possible to 
just replace that yellow ink with theUltrachrome equivilent and, remake 
profiles and the driver for everything, with much improved results. I just don't 
get it. I am completely satisfied with the CF inks rendition of all colors except 
the ones such as yellow, red, and orange, where intensity is needed in these 
hues.  This CF yellow also has much worse metamerism.The blues and 
greens are just beautuful to me and so much nicer than anything we had to 
work with in chemical color printing just as in Ultrachrome. Yea the Magenta 
may be a little weaker also but it is the yellow that is the big limitaion of this 
inkset for color control. Of course the black component is different but that's a 
different problem with different solutions.

John