Obviously they're handling more product at each step, but there are so many more steps and so many more miles, I could see it swinging either way.
My favorite thing about a farmer's market is that I'm talking to people with direct knowledge of the product and its production conditions. I can ask if the recent weather affected it, or what the outlook is like for the rest of the season, and usually get an intelligent answer. If something's advertised as organic or pesticide-free or whatever, I can get specifics about exactly what that means as it applies to this precise crop, not just a set of certification criteria that cover a whole industry.
And if there are ways to preserve that directness while making the market more efficient to get more products to more consumers without compromising the things that make it special, I think that's absolutely worth looking into.