How far apart do you space them?
Space them equally across the grow area. The size of the grow area and length of the strip would determine whether the grow area's x or y axis would work better. I have found seven strips give the optimum uniformity at close proximity (≈4") to the canopy.
You cannot limit you assessment of an LED to just watts.
That wall watts per sq. ft. is bullshit. Watts applied to light bulbs (e.g. HPS) Wall watts does not apply to LEDs. LEDs are not anything like a light bulb. Whole different ballgame.
lm/Watt at the same CCT and CRI is much more important than watts/sq. ft.
There are no CoBs that will have a better lm/W than a Samsung F-Series with the same CCT and CRI.
CoBs have thermal management issues ($$$ heatsinks), strips need no thermal management.
There are only a few Bridgelux CoBs that have a better cost / lumen than EB Gen2 and Samsung F-Series.
Height and Uniformity of CoBs are pathetic vs strips.
Strips can be as close as 3" to the canopy. CoBs typically more than 12"
Difference in irradiance at the canopy at 6" vs 12" is 4x.
Strips give you more photons per watt, cost less per lumen than CoBs
Strips can be positioned at a height giving you 4 times the irradiance of a CoB.
F-Series and EB Gen2 Strips have no thermal management issues at test current so do not need a heatsink.
Strips are better, cost less, and use significantly less electricity.
Which also means CoBs will give you a higher watt/sq. ft. but less irradiance at the canopy