Yellow is a recessive gene in labs from what I understand, but they're my favorite anyhow. Chocolates have genes even more removed from the original breeding, I believe.
Hell, I don't know. I do love me some labs though.

I've hunted over the gamut of all colors including red and white, and I found no correlation between their color and their personality or hunting ability. Some are absolutely retarded and some are really smart. Most are in between. Their (non-color) genes may be the biggest factor, much like with people.