a grow light is a grow light, is a rose is a rose.. not quite but... as far as how you assess them and use them.
Efficacy is what you pay for and impacts how many watts per sq ft you want.
DLI is the key. This depends on rate of photons applied (umol/s) and hours of operation -- rate x time.
sinjia?
Looks like 672 umol/s of PAR produced. 8-9 sq ft for 12 hour operation and 12-13 sq ft for 18hours operaiont. A lux meter can help even out distribution of light via hanging distance. Don't sacrifice overall average.
The shape of this light makes for hot spots down the middle and weaker on the edges more so than something with bars/strips of more distributed LED. cover a rectangual shape for best performance and reflective walls of course.