Ashton Crusher wrote:

[mixing colours to reach black]

The single Canon I tried did have both black and color carts. Yet it
insisted on using the color mix for black unless you did something to
force it to use the black - I forget the details now. You could work
around it but it was a pain to deal with and simply wasn't a problem
with the HP.

Did you ever look at the HP greys and blacks with a loupe?

And how do you correct for colour tints? Believing that every
black ink will be colour cast free under every light, in every
density, on every paper ...

The thing that surprised me most was that so many
reviewers raved about its print quality and it was clearly, at least
to my eye, inferior to HP for the 90% of the printing I do.

Hmmm, that looks like you did something wrong.
Or used the wrong printer for the task.
Or used the wrong ink.
Or used the wrong paper.

When
doing 4x6 color on glossy photo paper it did fine but no better then
the HP.

What else did you print? Text on recycled paper?

-Wolfgang