Cool! I never realized there where so many paint variations.
Yeah, many of them, IMHO, are practically unnoticeable to the naked eye. "Blue face Klaatu"? Doesn't look like any shade of blue I have ever seen.
I recently started at a photo collage of about 12 different Hoth Troopers/Rebel Commanders with supposedly different colored boots, until my eyes bled, but ultimately they all looked pretty much brown to me.
That's my only criterion for deciding whether there is a variant out there worth picking up - the difference has to be apparent to me. Paint, sculpt, etc.
All that COO stuff would drive me crazy...I could not care less what the little letters say.