I don't think that the coolness factor is a selling point outside of the low-end, like the cheap panel that OP linked, and these models are mostly 2010 surplus parts thrown together as a sort of low-info scam.
As far as things being proven for effective growing, I'd say that CFL's and HPS have been proven to be less energy efficient and less cost effective in terms of PPW, which is the reason to make the switch to begin with. You can try to dissuade people from looking into LED's at all, it will fail as the post-2015 stock (including COB's) becomes more widespread. Enjoy your 1970s-tier setup.
