QUICK UPDATE FROM THE EXPERIMENTER!!!!
If you can get true-white plastic that's thick enough for reflection, do it, it's only 2% better than flat-white paint but the results will speak for themselves. After all, those 95% reflectors you see are only 95% because you can see your reflection, so some colors aren't being reflected as a measure for reflectivity (most GOOD mirrors only have an 85% reflectivity simply because the material is made to compensate for lack of reflection in the true spectrum.)
White, as we all know, is the reflection of all light spectrums to our eye. Pure white walls, reflective or not, are the best way to go. I'm going to be taking down my mylar sheets because while I like the light diffusion and even spread, I'd rather have proper reflection and direction to plant chlorophyll.
Keep up the good work on the CFLs, bro! Fluorescent is the way to go with the latest T5HOs beating MH lamps lumen per watt. Photon density is truly important, but with the right configurations, fluorescent is more portable and positionable than MH or HPS lamps!
I say take a small set of T5s, like 1 or 2 foot, they're light enough to use simple tacks and such to hang them where you need them to be, and you'll have a great harvest on the undersides as well as the topside!
Take it from a former Hort. Sci. teacher - you're on the right track, my brother! We're so close to making fluorescent lights beat out HIDs, as they are both a type of HID bulb, fluorescents are just less powerful but have the same potential! They already beat out buds from LEDs with their 'focused spectrum' (but horrible canopy penetration,) so you know Fluorescent is quickly becoming the way to grow!
My 432 watts of 6500K bulbs growing pot and catnip and basil and mint is a testament to that! Keep up your work, Fluoro Brother!