I questioned some people that are very much in the know on lights and light energy. Here's what they said.

"The whole discussion in terms of lumens is pointless and not applicable to mj, or any plant. Nevertheless, doubling the lumen output in the same space will also double the lux (lumens per square meter) or foot-candles (lumens per square foot).

800w of HPS produces twice as many photons as 400w of HPS. This can be directly measured, there's no need for speculation."

and

"Light measured at the source is radiance. Light measured at a distance from the source is irradiance.

We are primarily interested in photosynthetic photon flux (radiance) and photosynthetic photon flux density (PPFD, irradiance). Other useful units are watts (radiance) and watts per square foot (irradiance).

Lumens are not a useful unit of measure of radiance for our purposes because the lumen is biased to human visual perception. The corresponding units of irradiance (lux, foot-candles) are also not useful."

Go figure. All I know is that if you had one 43 watt bulb in there that the plants wouldn't be as dense. Basically that's what you're suggesting that Zandor is suggesting.
Marc Benson Reviewed by Marc Benson on . 44,000 lumens and 728 watts of CFL's! I'm obsessed. I admit it. Too bad I have the dreaded "Black Thumb Disease". But the plants look like freaking Christmas trees! Lights hanging all over 'em! Not cheap to do it this way though. Just anal about cfl's. 12 43 watters 4 23 watters 1 40 watt strip 1 80 watt strip And here's a pic of what that many cfl's look like. Rating: 5