First,, thank you for commenting on my grow.
Now to your situation, at the time I decided to go with the COB setup I didn't know much about the 315 LEC,, but after checking them out on you tube I can say I would still go with the COB setup and mostly for one main reason.
With 4 or 5 seperate COB lights I can put them where ever I want in the tent to get the light just the way I want.
The COB has an adjustable damper that I can choose the amount of light I want without raising or lowering the light.
The single 315 LEC light has a lot of fall off in a 4X4 or even a 3X3 area. It needs to be replaced every 10,000 hrs and you can't adjust the amount of light. It is a nice light so dont get me wronge, it's just not right for how I want to use it.
I dont feel that 4 COBs would give you the ability to have even lighting over a 3X3 area. 5 lights would be better for sure.
I only have 3 lights on because I only have 2 plants and one seedling in there now. If I had 4 plants in there I would have all 5 lights on. In the end it;s up to you and I wish you luck which ever way you go.
G