What brand of leds will you be using and what price point are you aiming for?
i have made my own custom panels for the last year...they will be less expensive per watt than most
configurations either DIY , with passive heatsink, or with active fan cooling
right now its either 6 x 250w panels grid i run at 100w each and no need of heatsink
or two 250w panels[at 160w each] each with a fan ..
i am making some 320w panels because they will be cheaper
personally i like the coverage of the 6" x 22" run at 100w each
i do not waste energy raising them..icankeeo them close and the massive amount of 561c's penetrate extremely well due to so many points of light..being lower wattage they do not burn either..and just need a fan on the unit..even with no fan they do not get overly hot at all. than cooing.i would rather throw $$ at more leds and even coverage.
i do have 6 "x 22" passive aluminum heatsinks
i intend to see how may watts i can put i them and still be cool..so that i canhave a "one panel athigher wattage option"
i can slaughter 1700-2200 $ range and be 600-620 w including the solid aluminum frame and 600w driver..it easily covers 4 x 4
more like 5 x 5
i have a grow in the led section and photos of the proto types..i am satisfied they do very well..
ps. ...i do not want to get big ..thanks..they are doing better than hps for me
as well the plants are more healthy[not that hps isn't awesome] i have not had such fat dense sticky bubba buds etc.