Interesting thread. I found an article Rare Horse Colors ? The Facts
With some interesting stuff. I have a chocolate flaxen that I always thought was correct. From the article I'm not sure if she should be a chocolate palomino or a flaxen chestnut. She is a RMH and that registry calls it chocolate flaxen so I guess that's what she is.
As with most of you, it seems chestnut and bays are the most common around here in QH country.