I wasn't suggesting people go out and buy an Indigo.
The resolution is too low anyway for portfolios.
My point was that this technology for swapping out the cmyk inks for a quad set was sitting there for years and years ready to go, and established by HP for books. But small run book publishers are just now starting to use it for small edition books, that rival really good expensive tri and quad tone offset, and beats the cymk monochrome books being done cmyk in China for much less cost and much faster turnaround.
The HP Z printer for super permanent hi-res inkjet could be used the same way, easily, now, if HP offered the diluted gray Vivera inks for it and a simple driver based on what they have now, with the onboard spectro that they have now to linearize it. The carts are so small, and the heads so cheap that there is no big issue of doing that. What I have heard over and over again over the years is, yea they could do it, but there is no big market for it. That is exactly what Blurb and others were about using the monochrome version of the Indigo, until now. Once people see it they say, wow, I want that.
Installing an Indigo, depending on what you do exactly, can be a million dollar investment. Even done "cheaply" is many hundreds of thousands of dollars. You simply can't compare that technology with inkjet and say "oh, the press can do this, why not the printer".