Well, the shield itself drops output a few percentage points but I was referring to the heat issues. The Nova is fan cooled and the fan cooling in my original extreme was better than decent so I dont think that the output difference would be too signifigantly lower with the shield on vs. off beyond what par you lose due to acrylic itself.
But, the TEK is not fan cooled and they notoriously do lose a signifigant amount of par from heat build up when the shield is installed.
So, with the shield off of both the Nova and the TEK, I think the TEK will spank the Nova. As long as the shield is removed from the TEK, I dont think the Nova has a chance, with or without the shield on the Nova. IOW, I dont think the shield on the NOVA will make a huge difference. But with the Shield on the TEK, I think it will be interesting. We'll see. I could be way off.