on the subject of inda gro. If you look at the spd. Its lacking red in the 660nm range and lacking IR which both are needed for flower. between 660nm and 700 nm is where chlorophyl absorbs the most light. So you would still need to use supplment lighting , led or t5. If they tweak the gas a little, they could produce the 660 red.
You make a good point in that there is no such thing as the perfect man made lamp. They all will lack the intensity @ the full spectrums of the sun. However by managing lighting integrals properly and measuring yields against costs p/m squared I would be hard pressed to justify LED or T5 to 'supplement' the Inda-Gro PAR blends.
No matter what lamp technology or whose spectral distribution graph you're looking at its still data based on relative intensity of the wavelength at a specific point in the spectrum. Intensity is generated by energy. If you look at any HPS SDG you see that the relative intensity of HPS falls off steadily to nothing on wavelengths north of 630nm. This is not necessarily a bad thing but it's not a complete Red/FR solution and it does take alot of energy above PAR to achieve the red they do emit.
The predominant gas used in fluorescent lamps is an Ultra Pure Argon. Mixing Neon, Krypton, zenon to argon is usually driven by the requirements of the lamps operating voltage. The gas doesn't influence spectrum to the degree that the phosphor blends do. For example argon emits a far red peak in the 710nm region but overall influence of the gas, any gas, on the lamps PAR spectral distribution when measured in relative intensity is less significant then the phosphors. The Inda-Gro PAR blends emit red spectra up to 655nm which as you can see by their SDG is still higher then the argon peak. Ideally I look for a wide spectrum lamp that does emit a FR to not overcompensate the Red. The desirable ratio is 2:1 Red over Far Red as measured in relative intensity.
Besides gas and phosphor the small Mercury (5mg) amalgam present within a low pressure (when an EFDL lamp cracks there is no explosive outburst of glass. They just quit working and the crack tends to keep spreading) glass tube, typical of EFDL induction lamps, also provides SDG emissions @ 405,445,545,580 and 780nm.
Under an HPS lamp where the sodium mixes with the Mercury (Hg) (12-50mg) in a high pressure environment lamps explode when broken as the pressure is released, that same Hg reacts in entirely different spectra and are less predominant then in (8%) fluorescent. Check those mfg's of HPS and look at their Spectral Distribution Graphs. You'll find under high pressure Hg emissions contribute less then 1% of total spectra and hardly show up at all on the SDG. The point I'm making here is that when these lamps explode you have Hg spread all over the grow area and collecting the Hg from an exploded lamp will be will always be a question as to whether or not it was all collected or any remains in the room.
I'm not picking on HPS but do keep in mind that the lamp changes on an HPS that goes to it's rated life of 20,000 hrs compared to an EFDL @ 100,000 hrs is 5:1 in Hg as an environmental issue. Most growers change the lamps at around 10% of the rated life so the ratio is actually 20:1. Lets hope those are all being properly recycled and not getting into the ground water.