I sure can't answer on the bubbles, and there are quite a few more well-versed peeps in this forum than me, but certain hi-lite colors really bring out some cool characteristics.. For example, I use gold hi-lite in my CCM green with a drop of black for my baby bass back color and get a very realistic bronze-ish effect just like a real bass. It literally blew me away the first time I tried it. I'll say this- you sure don;t need much hi-lite at all to achieve insane results.
-Shawn