This is neat...
I think I've heard this kind of thing before, but not exactly this way. Maybe it's the examples.
In the tutorial, you've used the term 'vocal point' more than once. I think you meant 'focal point' like 'focus'. 'vocal' refers to sound, like 'vocal cords'.
I tried something with lighter and darker colors in a picture recently (I usually just pick whatever colors I think look good, but I thought I'd try going with really light focal points and a really dark background and keep it somewhat consistant instead of all over the place), but I think I ended up with some odd looking colors from trying to get the colors to match each other while at the same time sticking with them being as bright or dark as I was wanting. So I think I need to work on using color more.