I don't use any fancy devices, for me it's cut, drop in a glass of water and wait. But, the clones still have leaves which they use for photosynthesis, which in turn is what gives energy for new growth to the plant. Being that they're clones, the energy is used more for repairing the cut, hence generating new root growth, as opposed to new branches and leaves. Using that knowledge, I still say the more light you can give them, the better, provided you keep your humidity high for them to still be able to transpire moisture. I wouldn't suggest sticking fresh cuts directly under a 1000 watter, but mine get the same lighting as any other plants I may have going(I use strictly CFL's). Test it out a bit, see how they respond to nice bright light, or you may see some negatine results and use something a bit less powerful.