you should get some powdered aquasoil. it totally changes the whole aesthetic of a scape and makes everything look so much cleaner. it looks great so far though
*and IME it holds plants better
I agree with this. A top layer of powder type (1/4 of your total substrate depth) is very aesthetically pleasing and aids plants with finer roots (like HC) in rooting and spreading.
I hope your tank turns out as well as you envisioned it and that you took a wealth of knowledge away from Khoa's setup that you used as inspiration. I'm looking forward to seeing this develop. The stones look great!