I'm still scratching my head over the guy you know who uses red light at night... He does this flowering weed?
A lot of greenhouse farmers for other plants traditionally use red lights at night to keep the plants from going to sleep without having to keep all the lights on all night.
I would really like to see red on at night with weed, because it contradicts with the theory that 660nm red light brings Pfr to it's highest level. Of course I can't argue with results, but it's something I absolutely need to see before believing.
Nothing has ever led me to believe that using either red or blue light at night would be "Safe". Without seeing it, "completely dark" is all I trust for night time.
Did he have the red lights on at night specifically to keep it in veg with a shorter light cycle? I don't mean to question your experience because obviously your setup is amazing compared to mine, but I've always read that 660nm wakes the plant up like no other.