HD, If you're referring to the drawing I did there really aren't side lights per se but just a 'dome' over the top of the plants. Just to get into some extra nooks and crannies of the top canopy.

But since refectivity has come up, really, if we think that the light from cfl's is pretty much junk after a few inches, then the light that is reflecting off any reflective surface, really isn't doing anything as it pertains to increasing the rate of growth. I'm sure someone here can figure out what the power of the light waves are after they go say 1 foot to the mylar wall and then bounce back to the plant I'd like to have the time to do a test with black walls to see if there was any more/less growth vs. say mylar. Might just be hype like a 3.0 GHz processor being so much better than a 2.7 GHz. Basically the same. Now if we're talking mega watt/mega lumen mh's or hps's then I can see where a reflective surface may help generate sufficient lumens back to the plant after it's long journey.

Fun to talk of such things. It's the way new ideas and techniques are developed.