"What I'm missing in my research are LED grow logs from more than just a few people."

ICMag - 22w LED - 38g harvest. Pinstripe's 2nd try: PC case + 22W LED - International Cannagraphic Magazine Forums - my personal favorite grow. Second try and almost hitting 2g/w; that will beat almost every non-vertical HPS user all day every day.

"I'm not saying that this could replace a 600w HPS with the same results."

120w LED would grow the same-size plant as a 600w HPS, but you wouldn't yield like the 600w HPS simply because the 600w HPS offers its usable wavelengths in much higher photon flux densities than the LED unit. Now, bear in mind that most LED units are running 120-160 degree diodes (even mine are 120 degrees as I grow short plants.) However, narrowing the beam angle will create the necessary higher photon flux density. 120 degrees is good for up to about 2 feet maximum if the canopy isn't too thick. REALLY thick canopies won't get further than a foot or so. Bump to 90 degrees, you get up to three feet. Sixty degrees will go even further, almost five feet. Thirty degrees requires tightly-packed diodes but SWEET MOTHER it's almost like shining a laser in your eyes when you look at it, and it can grow some mighty-fine plants. Of course, with such high-focus panels, unless they are massive they're usually only good for one or two plants, LARGE ones yes, but only one or two.