Interesting discussion. I think it's hard for us to know how animals see color, and how they process what they see. Then there is the fact that animals are as individual as we are. While some responses by certain species may be fairly predictable, I don't think there can be any question that some individual animals are more intelligent, curious, wary, or agile than others of the same species. Natural selection, you know.
I avoid wearing blue in the woods, and especially blue denim jeans. First of all, the blue color really stands out... Apart from a few tiny flowers and small birds, the blue sky and its reflection on water, there just isn't that much blue out there, so it is easy to see. Second, and it is surprising how many people don't know this, many flying, biting insects are actually attracted to the color blue. It's hard to see ticks on darker-colored clothes, too. As for those denim jeans, they can get hot in warmer weather, and if they get wet, they get really uncomfortable and they take forever to dry. I've waded a few creeks and been caught in the rain a time or two while "out yonder."
I used to work bees with my dad many years ago. He always told me to wear light colors to avoid angering the bees, although I don't recall him specifically telling me to avoid blue. He did say to avoid black... "If you're wearin' black when you open the hive, they'll think you're a bear!" There's a good reason commercial beekeepers' coveralls are white!
I have been to East Africa twice, once to Uganda and once to Tanzania, both times as a tourist, not a hunter. Both times, it was mostly just my wife and me with a driver out for the day, but we stayed in group safari camps overnight. We were advised to wear "earth tones" and neutral colors at all times while in the bush. I saw some odd-looking contraptions out in the bush near our safari camp a couple times. Just blue and black fabric stretched over light box-like frames. I was advised that these were tsetse fly traps. The fabric was saturated with insecticide, and the blue and black colors were all that was needed for "bait."
On the other hand, everybody tells you to avoid wearing red because it infuriates the males of some species. However, all the Maasai men I saw in the bush wore a red cloak or "shuka," and they routinely walked everywhere, frequently alone, armed with nothing more than a stick!
I have no personal experience with elk and the color blue, but I tend to go for colors that help me blend in, rather than stand out.
Notchy Bob