Thanks for covering cost, heat and efficacy on point, still more areas where to look at when deciding between LED or HID like bringing out the best out of a strain for example thrichome rich cookies pheno, ofcourse high wattage HPS will foster a good frost but if cooltube is needed then the glass will block uv and instead of extra thrichomes that protect leafs and bud more likely results in light burn, with modern LED success is quaranteed.
Another issue would be differing in plant height like 2 out of 5 plants grow 1meter tall and 3/5 strech over 1.5meters, now you want a powerfull HPS that reaches far down with all the energy to support growth.
In the future I will invest in a LED but for this run settle with the 1000watt bulb baby
