I know from previous experience that even with neutralizing, my home brewed aquafortis darkens within a few days. The color will also deepen when I get more coats of finish on the stock. The picture above is with only one thin coat of finish.
I used the 10:1 aquafortis dilution on a test piece from the same stock and it looked like a piece of charcoal even after rubbing it back with 320 grit sandpaper.
I like a dark color on some stocks, but it seems to me to be a waste to stain a nicely figured stock so dark that you can't see any of the figure.