Digital BW, The Print

I'm trying to decide whether to go with a Carbon-6 type inkset or the 7800-EBHP inkset in my 4880. I'll be using QTR.

In his Carbon-6 inkset, Paul uses 2 channels of 30% Eboni, and three channels of 9% Eboni.  What is the benefit of using multiple channels of the same dilution?  Would using more dilutions be at all beneficial? How do the various dilutions of Eboni affect settling?

With regards to the HPPK and dilutions, how good of a glossy print do these make minus glop? (I believe that glop is fairly clog prone.) Would applying Renaissance Wax to the prints minimize bronzing enough to make high quality prints?