"New" Epson color inks

I have the Epson P800 printer and am very happy with it. Best of several Epson printers I've had. But I note that newer, high-end Epson P series printers add green, orange, and sometimes violet ink. Do they make a noticeable, practical difference? Would any of you upgrade for those?

The goal of such additional inks is to expand the color gamut. So yeah, depending on the source color space gamut, and the image, it can make a noticeable difference.

Green and orange are complimentary colors in CMYK. Including these colors allows a brighter print than mixing blue and yellow or red and yellow respectively. I presume that is an advantage for photos of landscapes and nature. I have not personally experienced their use. My Canon Pro-10 has pigmented inks in both light and dark versions plus a clear coat. That seems to work well, if a little darker than you might get with different ink sets..

Sorry, got nothing to do with brightness.

Brightness is a perceptual phenomena. The brightness perceived is based on the paper and of course the illumination. More inks play no role in this but they can affect the saturated colors perceived because they can increase the color gamut (range of colors).

You can generate green by the application of cyan and yellow ink. The saturation of the combination depends on the degree to which the two inks mix on the paper, or ideally, the absence of overlap of the dots of each color. With green ink, there is no question of mixing or overlap to detract from the results.

Do they make a noticeable, practical difference?

Much likely "yes". Based on my impression from the graphics design world, where they have horribly expensive examples of attempts to 4c print Pantone tones and others of the same tone printed with properly mixed dedicated ink, that can look pretty far apart from each other.

I would try to beg Epson for convincing samples via mail. Or contact a dealership, if they are able to convince me, by showing some.

I am not overly enthusiastic about colors and especially not about homeprinting them but YMMV.