I think the point of using LED's (for me at least) wouldnt be efficiency of growing bigass plants, but instead, the almost zero heat generated.

Imagine a set of 6 large speakers (the 2.5ft tall , bigass ones)

In the bottom, you have walls lined with LED lights, on every side, and a lowryder/lowlife in the middle. no vents required, just a burping everyday.

in the top 6"? an actual working speaker

if you get 1oz / plant, and have 6 speakers, you'll be getting two thirds of an ounce a week, enough for a light/weekend smoker, and a reasonable amount for a medical user.

its the perfect stealth setup, nobody would ever realise.