I doubt you'd be able to tell the difference from the same wattage of a Cree COB, for instance, maybe slightly higher. I think you're over analyzing things though. Just hit em with about 50w/ sq ft of any brand of COB and you're gonna be alright. It's not really a precise science, just blast the fuckers with as much as they'll take without ill effects or excessive heat, is my advice. I guess the figures would be good for reference purposes though, to to know. I dimmed my lights from 50w to 75% with PWM and I just got reduced yield. Now I put em back on full power. So what if the top parts get a little bleached? The bottom parts also get more light, so you take the bad with the good. I wouldn't go over 50w though, because that's actually pushing it, at least in an enclosed chamber lined with mylar.
Actually, since I read in one report that pulsed light avoids light saturation I may try a duty cycle of something like 99%. Same amount of light, virtually, but never on for more than a few hundred microseconds at a time. Probably make no difference, the plants used in report were lettuce, as I recall, which probably saturates a lot easier than weed. Worth a shot though.