one thing is spread of light. chips on board leds which i used in a tiny 1.8ft by 1.8 ft scrog had 4 50watt cobs (home made rig- that kinda looked a little ugly but worked) had light coming from all corners and i really should have hooked it up with a dimmer for veg stage…anyway light from different angles such as cobs placed and suited to your setup will spread and hit more plant tips from all angles…on other leds some leds such as spiderfarmers can be raised to get more lumens and intensity of light to outside edges of setup…lowering can increase intensity and par reading in the inner but raising will often raise par reading on outside of tent etc…im looking for one to buy myself, my home made ones the meanwell drivers often shat themselves after 8 months and apparently meanwell quality went downhill and failures became more common…
i dont know if people still use cobs as others coming out are cheaper to buy than making a cob rig…however i had good results sometimes with cobs, but often too much par reading and bleaching as too intense…should have bought a par metre and a dimmer.
8 ounces from 200 watts isnt too bad imo in 1.8 ft by 1.8 ft though so it sometimes got decent yeilds.