I've got a guy local who builds them. Gonna go see him and see what he has to say. So cob is the way to go it seems. I'll do a side by side with gravitas if I have a panel or 2 made.All of the blurple LEDs are total crap. All of them. Check out opticlighting or you could just ask SupraSPL what he recommends. I've been using some optic lighting in my veg room and also in my flower and so far so good. My light meter tells me they are nice and bright too. Not as bright as my gavitas though.
COB based LEDs if you go that route. Otherwise not worth it.
Gavitas still superior I think in terms of cost to output but that is changing.