The term organic has nothing to do with the quality of the feed. It has to do with how the elements of that feed were grown. To be certified organic the feed has to be grown pesticide free and I think GMO free. Other than that, the organic feed can be composed of anything, thus it does not have to be nutritionally balanced to be organic. Same deal with humans. I could get organic Twinkies and still not be eating healthy food.
There are very specific rules that pertain to marketing food as organic. You actually have to be certified by the gov't and take serious precautions to make sure that your animals/product aren't cross contaminated by neighboring farms. I am surrounded by crop land that is sprayed and whatnot. It is unlikely that my tiny farm could ever be certified organic since I am sure there is some contamination from the neighbors. Most people give up on the organic label and go with "cage free", "free range" and "farm fresh".
As to quality of food, I had mine on the Purina brands for a while. Every chick that I hatched had wry neck problems and my adult chickens just didn't do as well. I switched from the Purina line to the local co-op brand and have been very happy. I feed my breeding lines the 21% protein co-op pellets and they have done great. The 18% is also good. The sales people are trained to tell you all sorts of stuff. I would question their "expert advice", especially if they themselves did not have chickens at home. Try several lines until you find what works best for your birds.