55$ to try is not bad at all. It seems like their brochure, and the daylength extension study are focused on a slightly different question (convincing a greenhouse plant that it's still daytime) than just providing all of the light for indoor cultivated plants. It's still confusing for me, because Philips in their brochure lists the DR/W/FR photon flux as 15 "uMol/s", I'm not sure if they really mean uMol/s/ m^2. But in any case, the question for me is, how many of these are needed to adequately illuminate a 2 x 4 foot shelf of plants? If you look at this link:
http://www.apogeeinstruments.com/conversion-ppf-to-lux/
15 uMol/s/m^2 is supposed to be equivalent to 1100 lux of cool white fluorescent, Philips reports a nominal 3200 lumens for a single 4 foot alto t12, but it's unclear whether that is lumens/m^2 (lux) or not. If it is, that would imply 12 (!) of these would be needed to match the light output of 4 t12's, which seems hard to believe. Long story short, do you have a PAR meter? If you do, and you'll do comparative readings on one of these and a fluorescent tube, I'll buy you the philips led lamp. I tried to get my local aquarium club to group buy a PAR meter to no avail. I guess buying one and just seeing what it can grow is reasonable, I just wish it were easier to predict what you can expect (or how many you need) per shelf.