I dunno. Naturally most of the bud characteristics come from the genetics. I think good light penetration comes into play in making denser buds is purely from more intense light of the leds and more of the light being utilized by the plant. I don't know much about cobs, but from what I understand, the light is fairly focused. You get very little reflected light. Even with the 2014 California Lightworks SolarStorm 220(VERY BURPLE!), I can see the color under the HBSS girls. That's even with the SP3000 cranked 100%........so lots of reflected and penetrative light! And that's on to the leaves. Hitting the buds is just secondary.
Just my thoughts,,,,,,,,,,,,,,,,,,doesn't mean they are correct!