I'm still on my first grow, and have a decent amount of room to mess around with, so i can't comment too much on 'compact' grows.

My concern with the Rubbermaid box type grows is light penetration. If you turn the lights off in the room when the lights in the box are on, and you see any light, i would think that means light leaks for the opposite situation... dark box, light room.

Not sure if people usually paint them or whatever.

Of course this won't matter till flowering so you have a bit to figure it out.