COBs with 110 degree light output are not well suited to a design that requires light in a 360 pattern..
And that is were the main error in your imaginary design lies, the 360 you assume is not required at all. Vertical bare bulb equates to a 360 degree light pattern. There's no reason vertical cob grows should too. People don't choose 360 when running vertical, it's a default result with bare hps. There's no valid or logical reason to apply that 360 (which by itself says nothing about vertical vs horizontal obviously) to COBs. In fact, it's dumb. Considering we tend to work in square/rectangle space, using a circle within a square is not an optimal use of space. You can use four walls in the cube surrounding the circle instead. The bare bulb vertical setup is to use the bulb and space more efficiently. Once you no longer use that bulb trying to apply that misuse of hps to led is just futile and silly.
This whole thread reads like slapstick... Both the attempt to reinvent the wheel (instead of going for top lighting in combination with inter lighting as widely applied by pros), and the desperate arguments from the led fanboys that it's not a fair comparison. The fact led is so directional and you have multiple light sources is an advantage for a vertical setup where it essentially becomes side lighting, which in case of cannabis should obviously not be the main light source. Besides that there is no valid reason to do only side lighting once you take the bulb out of the setup...
=================== access path
^^^^^^^^^^^^^^^^^^^^^^^^ cobs side
***************************** cobs top lighting above plants
vvvvvvvvvvvvvvvvvvvvvvv cobs side
^^^^^^^^^^^^^^^^^^^^^^^^ cobs side
***************************** cobs top lighting above plants
vvvvvvvvvvvvvvvvvvvvvvv cobs side
^^^^^^^^^^^^^^^^^^^^^^^^ cobs side
***************************** cobs top lighting above plants
vvvvvvvvvvvvvvvvvvvvvvv cobs side
=================== access path
That's the way to go.
Shows again how blinded folks are by the attempt to "beat hps" and how obstructing that is on a path to apply led properly. Same thing happens with normal horizontal grows... Finally you have the freedom to control the light direction and you still point them all straight down.
Pretend there never was hps, instead of building on the bare hps bulb artifact '360', and consider how the plants, not a surface horizontal or vertical, are best lit.