Ha ha! Nothing is ever simple is it? The bottom line for me is a practical application. For those who use a transparent fermentation vessel, what is the maximum exposure to average (I know...) indoor light (where most fermenting & bottling occurs) without off-flavors occurring.
It seems this would be fairly easy. Have brewers detail every bit of time the wort/beer is exposed to light, with some designated for specific periods of time (i.e.: 5 minutes, 10, 20, 30). All one would have to do is open the cloth covering, open the door or whatever else is blocking the light.
I guess I am arguing for the middle of the road approach - something that would be indicative, but not worthy of publishing in a peer reviewed journal.
Incandescent light, no worries. Daylight and fluorescent is what you need to worry about.
What about LCD lights? I'm thinking that many brewers, like me, have converted all their incandescent bulbs to LCD.
Good question, Frank! Unless someone here pops up with an answer, I'll try to do some research see how they compare.