dg problem though, Andrew, is #2!
Well we still don’t know that the values are that close since they are being generated by different products. However, depending on the imagery (say a gray), its not unlikely that even small value differences would appear differently. If we knew that the values were all generated the same way, we could use the XYZ values to generate a deltaE value to inspect the differences which might be useful.
Its not at all uncomon to find two different software packages, all set for the same target calibration values using the same instrument to produce different results. I know that’s not supposed to happen but it does.
What many users also don’t know is that you can buy two different Spectrophotometers or Colorimeters from different companies, measure the same color and get different values! The manufacturers all use different ways to get to what we think is the same results. A new ISO spec (ISO13655 M0) is supposed to remove this disconnect but guess what? If you buy a unit today that doesn’t aim towards this spec, then a year from now, buy a newer instrument or even have your old unit repaired or recertified, its quite possible all the data you measured a year ago and all the new data you measure will not correlate! That’s a big friggin issue for many of us.