Digital BW, The Print

So many people seem to have clogging problems with MIS inks (me included) that it begs 
the question as to what it is that these inks lacks that Epson UC inks have.  Even their UC 
equivalent inks clog like hell.  It has been mentioned here that one way to get rid of a 
persistent clog is to reload Epson inks.  So what gives?  Why so many problems with the 
MIS inks vs Epson?

(Please let's not turn this into a why use, at all, MIS inks vs Epson...)