2019-08-28 by brian_downunda@...
You will face some interesting choices given your preferences and constraints.
As you probably know, K7 uses seven shades of ink, shade 1 being the darkest and shade 7 the lightest. There are two shade 1s - one for matte and one for gloss / semi-gloss. K6 uses the exact same inks but leaves out shade 7, and so the QTR curves are different because the six inks are used to cover the tonal range from black to white rather than seven. If you have K7 installed you can print K6. I've never been been able to find an image where I can see a difference between K7 and K6 prints.
P2 is K6, but with shade 1 for PK in the slot where shade 7 used to be. This means that when switching between MK and PK you don't have to switch cartridges. On smaller desktop printers like the P400 you need to pull one cartridge out and insert the other. On larger printers like the P600, P800 and beyond, you need to do the MK/PK switch. P2 means you never have to do this. So the P2 curves for MK are just K6 curves and the P2 curves for PK are K6 curves reconfigured to draw shade 1 from the yellow slot. P2 makes a lot of sense for those printing with both MK & PK, but is of no advantage if you only plan to print with one or the other.
Since you're only going to print on glossy / semi-gloss papers then the Pro inks have a huge advantage in that the gloss overcoat is applied at the same time as printing. This is called one-pass GO. K7 and its variants currently have a two-pass GO, which is a right pain. You print, and then you print the GO overcoat in a second pass. Things can go wrong and in any case I don't think that two-pass GO is as effective as one-pass. One-pass is a *huge* leap forward for Piezography on gloss / semi-gloss. Walker Blackwell has said that a one-pass version of K7 is under development, but it's been that way for a while so don't hold your breath.
However you won't get selenium from Pro inks. Pro inks have both warm and cool tonings, which you can blend and / or split tone. The only tonings available in Pro are those on the warm-cool axis. There is a selenium toned inkset for K7/K6/P2, but that means two-pass GO.
So this is the choice you currently face - one-pass GO or selenium?
I can't shed a lot of light on the Pro vs K7/K6/P2 question. From a little experience with Pro and much more with P2, I don't think you lose a lot with Pro. I honestly haven't seen an independent assessment of this. Most reports of Pro are either enthusiasts or closely associated with IJM. Now if Pro is as good as K7 etc, this calls into question why go Piezography rather than OEM (K3) if four shades are as good as six or seven? Good question. OEM-QTR-K3 is pretty good, esp on the P800. Part of the answer is that Pro
isn't really K4, you're typically using both warm and cool inks in some combination in a
print, and so Pro is laying down inks from seven channels. But there are
still only four levels of tone. So go figure. There really isn't an answer to this question.
I opted to go Pro because I decided I wanted more control over toning. What you will find with K7/K6/P2 is that what appears to be a subtle toning on matte paper is quite a lot stronger on a gloss / semi-gloss paper. This is particularly true for Special Edition inks, and to a lesser extent with Selenium. With Pro, I can tweak the toning for PK papers to dial the effect down and get roughly the same effect on both types of paper.
I don't regard the P800 as a great printer for very intermittent use. My experience is that the Piezography inks settle without frequent use, and you will then have to waste a lot of ink by flushing it through the lines. There are nine lines and there's 10-15ml in each line between the cartridge and the print head. The same is true for hibernating the printer with Piezoflush. You've got to flush a lot of ink out to get the flush through, and then flush a lot of Piezoflush through to get the ink working. I honestly think that the P400 is a better option for intermittent use, unless you really need 17" wide rather than 13" wide. But as we discussed here recently, the smaller cartridges on the P400 are potentially more problematic than the larger carts on the P600 or P800, so again you face a choice.
For intermittent use you may be better with OEM, because my experience is that those inks sediment much, much slower when left idle. It is possible to simulate selenium with OEM inks - I have a QTR curve that does this.
I realise that you already knew some of this long rant, but I wrote a complete response for the benefit of other readers.