This is the same formula used in the HPS/MH light intensity charts that we've all se

According to the Inverse Square Law.

Using a 23-26 Watt 1600 lumen bulb.

1600 lumens at 12 inches

at 6 inches we get 6,400 lumens

3 inches we get 25,600 lumens

1.5 inches from bulb we get 102,400 lumens.

.75 inches we get 409,600 lumens.

With these numbers I think it's safe to say that using supplemental side and middle lighting adjacent to foliage with an HID hung above the canopy will have a nice effect on your crop to say the least.

Given that bulbs would have to be at least 5-6 inches close to get adequate lighting and at least 3 inches to get awesome or what may even be considered surplus lighting, cfl bulbs would only be effective for foliage in the immediate vicinity - though the extent to which this efficiency goes according to the numbers above is clearly more then efficient.

After all, a lumen is a lumen, like an inch is an inch or a meter is a meter etc, etc. I believe atm the general consensus regarding the intensity of cfl bulbs fading quickly has more to do with the bulbs having low intensity to begin with then actual science.

This is the same formula used in the HPS/MH light intensity charts that we've all seen so I'm confident that this is correct although I'd be happy to get a friendly debate going as I do have some other references I'd like to add.

where did you get that lumen data from....? so at 6 inches your 23w/26w cfl is kicking out 6400 lumens where the average 600w(26 times bigger) is at 117138 Lumen, use the hid and see the yield

Yes that is the chart. The inverse square is roughly as follows: For twice the difference away from the source light is reduce to 1/4 it's initial strength (this applies to any form of intensity). If you follow this formula for each of the light intensity listings respective to distance on the chart you'll find that the numbers are very similar.
Example: 1000 watt hps @ 4 inches is 400,070 lumens.
The same 1000 watt hps at twice the distance (8 inches) is reduced to 1/4 it's initial strength 100267.5 rounded up to 100,268.
I applied this same formula to CFLS.

So no other takers huh? I'll try to bump it a few times JIC.