some good info above on the blue. I learned how not to do blue on my sweet spot. it turned way too dark and I feel like it was a fail, in stride tho.
one of the things that I stumbled into and haven't had a chance to really make use of is tinting my tru oil. it's what I did on the last step. saddly, the base was already too dark. I didn't actually tint the tru oil... I just put blue leather dye on top. what I liked about this is it really changes color depending on the light.
When I get to do it over again, I'm going to do a much lighter base and a lighter tint on top of true oil. Like you've outlined above... seems like with dark colors you really can't see the grain... so I've learned that on my build and again here how I might get the darkness without dulling the finish - thank you for that!
I would love to try what you did above, and will someday, but I've no sprayer at present... so storing that away. for the record your end result is stunning and about the most 3-D I've ever seen.