If you can physically see light coming through a leaf, how could it NOT be taking in light? (top vs bottom).
I always run a few strait tubes down the bottom of the pots under the main stem and point them up. Encourages wonderful growth. You always notice when you do, vs when you don't use them, And they are only 15 watters.. just providing a bit of ambient light.. acting like steroids for your more powerful lights to bounce more energy all over the place.
Same with reflective light. I wouldn't go as far as putting mylar over the soil because you want the soil to breath.. BUT, there is a reason people use light colored stones in their setup as well.. ALL reflected light, even if just a tiny bit, is 'good' in teh indoor environment.
Just keep thinking of ways to maximize your light.. you are on the right track.. that said, sometimes it is not as efficeint, but more productive to just bombpard them with light at the source.. if you feel deficit down below, grab some small cfl or a few floro trailer tubes like I use and just set them under.. they indeed embelish and help increase noticeable lower trichome production as well. Things will look healthier and happier if you get lights down there, specifically the 6500 spectrum.. just seems to keep the bottom lush, green, vibrant and smelly..
That is just one ramblers thoughts. Everyone else's own mileage may vary.
