Not even close on lumens per watt.
All these threads about lighting...
I think I no longer care about lumens per watt.
Lumen = amount of visible light
emitted
Lux = lumens per square meter at the place where you want the light.
I did some measurements with a lux meter, and the results surprised to me
I converted the light standards above my vacs from 400W MH to 105W CFL.
Lumens reduced from 23500 to 7150.
MH measured 8 lux, CFL measured 6.
To the naked eye, I could detect a difference (side by side) but not much and only from a distance.
I know those are low lux #s, but standing at the vacs I took out a book and could read it with no hesitation. Visibility from the street sufficient to identify people & see details of what they are doing for security purposes was no problem.
I'm still doing measurements and evaluating my methods, but at the moment my conclusion is that lumens are not what we should be counting.