I found They give off less heat,less smell, so you spend less money on electric, nutrients etc in the long run,cost you more to start than traditional metal halide/HPS but one light does it all for you,mother's,clones,veg and flowering...they pay for themselves on the first one..the main factor for me was bigger yeilds,I looked into them for a few yrs and was sceptical at first..tested out a few from different manufacturers using a mixture of both and against each other,using the same clones/ environment,growing media and feeds.. and when LEDS were used we had bigger yeilds everytime ...the o