I don't see what light has to do with the pot size decision. Weather using a 1000 watt light, 400 watt light or using natural sunlight, that wont affect any of the factors I can see to determine the size pot, or amount of
growing medium used to grow the plant. The only possible relation to amount of light VS pot size (and thus amount of growing medium) I can see is more light will be able to grow a larger plant. But even then it's not the amount of light, it's the size of the plant that's the determining factor (in that one comparison factor, and assuming all other growth factors are the same).