Understand all that, but my underlying worry is the actual pigments Laurie, as you know, I've been around paints all my life, all I ask is that the pigments be the same across all the colours of that name, with this simple rule, I am able to work, knowing that despite different extensions (ratio of pigment to medium) I am working with a colour that, once sufficient coats are applied, will look the same!
But also notice my points about working windows of paints, and this is a bigger issue for me, or at least, my enjoyment of this hobby. Those colour comparison chards surely have their uses, and are a great guide to whats out there, but I crave a quality printed chart, its like comparing photographic slides to prints, the fact that one is, by its nature, illuminated, makes them appear very different.
As I've always said, the perfect colour chart will be made from the actual paint in question, and whatever paint I settle on, I will make one for my own personal reference! Rambled on a bit, sorry!