I think you will find that on hard curly maple, the only stains that show little or no wear, or loss of color, over time are aquafortis, and chromium trioxide. Anything else is basically a tint at best, and a color wash at worst, both susceptible to wear, and sun fading. With the earlier mentioned chemical treatments, over the past forty years, I have had great success, and dismal failures. These methods are sensitive to differences in wood, length of time between application, and heat flashing, as well as length of time heat is applied, and the heat source used. Neutralization is another whole topic in itself. I am very excited about the use of vinegar in place of nitric acid in the making of chemical stains. And, though my batch that I stirred up the day I read about the method in this forum, hasn't been tested yet, I have great hope for its success.
I think many of the beautiful long rifles we see with such depth, and color intensity, are the product of layered colors, developed by the use of acid stains as a base, followed with tinted shellacs, or varnishes, layered on top, to produce the color, and depth. JMO.
Hungry Horse