Personally when I use my zxmean lights beneath the canopy aimed up they got a nice almost shiny gloss and got darker.
Light leaves got color again to a degree for example. I was going to print off some leaves on my auto before and when I gave her a UV bath she made those leaves dark enough to get energy from them properly again. This was at the end of flower when she was ready to be chopped in a few days too.
Any plant I've tried it on only responded positively and growth tended to explode after when I was stuck at a stage. I can't say how effective it would be on a full grow as I've been using it as supplemental lighting occasionally. Maybe in a future grow I'll try one for it's whole life with light from beneath and above and see how it goes.