Dr. Beau,
As far as nutrient values, studies have been performed that document Vitamin C levels as high as 52% above conventional farming methods, and as low as 6% below conventional farming. One such study that documented significant statistical differences was published in the Journal of Agricultural and Food Chemistry, by a team from the University of California, Davis. The bottom line is that proponents of either side can pick studies to support their conclusion.
You are correct that certain pesticides are certified for use in organic farming. However, it would be an error to conclude that pesticides are used at all organic farms, just because they are certified for use. A study, albeit informal and not scientifically documented, has found that some farms do not use pesticides, while others have a varying use of pesticides. The question is how, if at all, does a specific pesticide residue impact health.
I live in the Los Angeles area, and there are local farms that use both organic and conventional farming methods. Thus, I’m not entirely sure why you attribute local foods to only conventional farms. Also, flavor has much to do about ripeness – not necessarily how recently the crop was harvested or how far it travels. On a number of occasions, I’ve seen locally grown produce (organic and conventional) that were picked too green.
Taste tests conducted by researchers from Kansas State University, indicate there are no ‘significant’ differences between the two methods. Another study by Richard C. Theuer in 2006, albeit perhaps biased, mentioned that past studies indicated no ‘significant’ or ‘consistent’ differences. Notwithstanding, the words ‘significant’ and ‘consistent’ indicate measurable differences. Thus, it would be incorrect to say there are absolutely ‘no’ differences. This is not to say the differences make a particular product taste 'better.'