My anecdotal evidence has been more from the production side. I saw how "roundup-ready" soybeans flooded the market, pushing regular seed developers out in the late 1990s. Oddly enough, these "superior" beans actually produced 15-20% less yield, and cost three times as much to plant and maintain.

I believe, deep down that their supposed "can't feed civilization without it" benefits is at best marketing, and at worst, part of a plot to monopolize food. Either way, I have seen the "yield increase" (without which we would all die of starvation) that Monsanto hangs their hat on to not only be exaggerated, but a complete out and out lie.