Digital BW, The Print

Please help me to understand this:
I can see that dedicated solutions like MIS inks will beat usual OEM solutions easily. But what about this new printers like the Epson 2800 or Hp Z3000 that have the 2 blacks plus 2 grays and use 3 of them to make the prints? (meaning nutral prints only). Since we know only 3 shades are necessary to print smooth BW,why a dedicated printer would do any better?
Who has experience with the 2880 using MIS empty chipped cartridges and K4 inks? Any significant differences for a dedicated system. And going this way can I print with just the black/gray inks with no color inks being throwed on the paper? I do have ColorByte PrintFix to make the profiles...
I ask because after many years I'm about to change my 1160/FSN for something new, 13"is enough for me, and I want to print color sometimes... And the choosing is torturing me...(OEM inks are not a choice...)
André