Yield depends of strain and stile of growing. The gr/watt ratio depends of lamps efficiency (150HPSs or Enviros are in a different leage than 600 or 1000w HPS).

I use a good producer (NL) in SOG, without any veg, with CFLs (DuluxL 55w) and obtain about 0,35-0,4 gr/w (real watts, total consumed watts) in 2 months (about 0,2gr/w per month).