For instance I attached the my JBC screenshot in (according to me) best condition.
The real problem is that particular type of color (very light cyan) don't activate all sub-pixell.
You have found a case in which Triton display responds to 600x800 resolution.
If I was Ectaco I'd resolve this problem introducing a contrast feature like the one on Sony-PRS650. In reality e-ink is not a contrast adjustable device but what Sony real do is to adjust the raster output before it came to screen.
P.s: this is a perfect text to use "reflow" feature. I see Reflow+Zoom solves the color problem but I know it is not a final solution