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HPS lamps are not as monochromatic as LPS, but they are still highly slanted to the yellow / orange end of the spectrum and are not good for plant growth. As the article notes, growers use 400 watt MH (Metal Halide) lamps. These are also the lamps generally used over larger salt water aquariums because their spectral distribution is more even.

If you are interested in getting a better crop, regardless of the plant, MH is the best, not HPS. However, I believe that I read where a better yield will be had with the inclusion of some other lamp types to round out the spectrum, specifically quartz (incandescent). When I learned about this, my focus was on commercial and industrial lighting, not farming, but some manufacturers at trade shows were showing their wares to indoor gardening operaters.

Actually, outdoor stadiums use a combination og MH and Quartz lighting when they need to up their Color Rendering Index for night TV broadcasts.

Finally, the article also points out that sellers were questioning the number of 110 volt lamps sold. This may be true for quartz, but all discharge lamps are the same irrespective of the line voltage supplied to the ballast. The lamp doesn't know if you have 110 or 277 volt lighting in your building, it's the ballast's job to convert line voltage.