I haven't seen light bleaching and I've run >1300µmol at times.
My understanding is that bleaching was not uncommon using HPS. The only time I've seen "bleaching" discussed with LED's has been from Bugbee and, just recently, Hawley (Fluence). Both sources found the same cause - very high light levels of 660nm light.
At about the mid point in flower for my last grow, I added a set of Spider GlowR80's. By adding the R80's, I was able to get 300µmol of 660 on my grow for 80 watts. That allowed me to reduce the input wattage on my Growcraft by 160 watts. The reduced input wattage + the improved efficiency of the 660 lights (newer diodes and 660 is the most electrically efficient diode) resulted in a > 2° drop in ambient temperature which ensured that my cola temps were well under 78°.
The spectrum for my main light is shown below. The 300µmol from the Spiders would be about 30% of the photons hitting the canopy so the peak in the red region would be significantly higher.
The PPFD values for that grow were posted upthread. Below are the PPFD readings for day 86. None of the values are >1100 but most are >1000. Even with a very high % of red and at PPFD's over 1k, there was no bleaching. That's only one plant/grow, granted, but I've used the Growcraft for about a dozen grows now at 1kµmol and never seen any sign of bleaching. Both researchers stated that the issue was that the appearance was off but there was no difference in potency. During the Bugbee interview (I think it was with "We the growers"), one panel member jokingly suggested that they market is as some thing exotic, as it if was an albino strain.
