I have a 4 bulb vanity fixture ($15 at HD/Lowes) using 2 x 300s (2@ $15) + 2 X 43s. The plants outgrew the height (3 ft) I have above the aeropods), so I moved the fixture high up on one side- horizontally, until 2 days ago.

After reading about the importance of light penetration into the leaf, and that underside lighting was benefical to get full penetration (I assume to allow the leaf do 20% more work), I turned the fixture vertically.

I think I am getting a better light spred this way, while at the same time lighting things up underneath. If anyone is interested, PM me, I have a journal on another site.