its really hard to estimate what someone else will yield with so many variables, soil, light, nutrients, genes yadda yadda...I just did my first grow with 200watts HPS, with quite a few CFL supplemental lighting. They were about the size of your smaller ones when I switched them to flower. I just harvested one early at about 6.5 weeks in, and it gave me probably like 3/4 of an ounce, and the other one is still going for another week or so, which I expect based on the one I harvested and the look of it to probably be around an ounce of nice buds, not to mention the shake and fluffly stuff on the bottom. So with your 600 watt light, i would expect a larger yield than that, so good luck. you also have more plants feeding off the 600 watt light, wheres I only had two plants soaking up the 200hps and cfl. something to consider there too. I don't know what you are going for, but me being a first timer, just growing some personal smoke, I was pleased with an oz per. so I think youll probably be happy.