Green is one of the top scorers in colour blindness tests. A large portion of which classifiers as green/brown colour blind. That is when greens and browns get to a certain tone, they can not see the difference. A big problem when trying to find a "proper" olive green.... Or olive brown.....Wonder why it is always green that gives the arguments.....
Apparently, some are so badly affected they have real problems with the classic RAF dark green and dark earth camouflage seeing it as two tones of the same colour!!!!
To get back to the question, Xtracryix have most of things down to a good match. Some of their armour colours are way off though.
If you dont have issue with enamel paints. Sovereign hobbies colour coat paints are as good as they get. All matched to original manufacturers colour chips.
I used to get far to hung up on colours. these days its. "close enough".