A 36" SolStix Rack with 7 X2s or 5 X3 strips with a 320w driver is roughly equivalent to a 600 hps over a 2x4 ft footprint. Except that you get twice the effective useful light output with 40% less electricity and 60% less waste heat.
Most HPS growers that fire up a SolStrip rig just put their old gear in a box and never look back. Its not much of a contest - kind of like going from kerosene lamps to electric bulbs. But there’s quite a few grow logs here on OG using SolStrip systems, you can judge for yourself: