Ah the x-rite software doesn't let you run tests on non-calibrated monitors like badass does with the lacie software (I'm using the same colour puck though). I've just done a new calibration on both monitors side by side and tried to get them to 6500k white point, 2.2 gamma and 120 luminance.
Default settings:
brightness 80
contrast 90
I had to use these setting to get the contrast brightnes and white point to the defaults
brightness 0
contrast 98
red 150/255
green 115/255
blue 131/255
Leaving the colour channels at default but putting brightness to 0 was still too bright, it was reading near 150 luminance

Sometimes setting the colour channels so far from default can give issues with colour banding etc, I'll need to use it for a while to see how it goes and maybe recalibrate at the weekend.
After calibration I get these figures from the two screens
215TW - average dE 0.61, highest out dE was the blue channels with one hitting 2.0
ZR24W - average dE 0.66, highest out dE channel was red at one hitting 1.76, also some blue colours where over 1.3
Again the monitor hasn't really been used much so might settle down? and I'll try some other settings in a few days to try and get them both more accurate. Personally they are now both accurate enough for some hobby level photo editing (hey I don't sell anything).
I haven't tried any gaming yet, grabbing a window that straddles both screens and shacking up and down (rough test

) shows it to have less immediate lag than the 215 but then this was always the weakest area of the older screen.
So far a thumbs up considering the price.