Not a flame, but unless you're not printing enough routinely of things other than gradients or facial tones..... how do you see this as a smart move to eliminate what the manufacturer of almost every machine on the market on the entire planet sees as a good thing ??
When you sue only CMYK, do you think there is a cost savings ??
You do realize... and I think if you can rebuild the machine, you can understand this....... if you need X amount of inks to make a color, that when using 6 sources, they all need a little less to produce the desired color vs. more of each color of 4. What it basically boils down to is you might see a penny or two difference in costs and unless you're using 12 liters a day.... it won't show up in the grand scheme of cost effectiveness.
If you're one of those with the mindset that it costs $105 to replace a liter or 440 cartridge, then just do as you see fit, cause you cannot see the forest for the trees.