I've grown organic hydro. I had some crazy ph swings for a minute there, but I was also working with new products (citric acid for ph down) and I never changed my rez or flushed or anything. General Hydroponics has an organic line called General Organics. I used the plain grow formula throughout the whole grow and I got pretty good results. I'll definitely be refining it so I won't have as many difficulties this next grow, but it almost feels like the findings of organic hydroponic growers mostly get overlooked. The hydro section really needs an organic section so that people can get this stuff down.
And I doubt that a plant looks at organics and synthetics all the same. Originally they thought NPK were all a plant needed; Now it is known (although not recognized by the USDA) that plants grown organically produce more polyphenols (which is beneficial to the health of the plant, and even to the consumers [eaters, not smokers] of the plant). If the plants looks at ferts all the same, then why are the chemical compositions of synthetic and organic different?