I haven't seen anything on subsistence farmers in particular. The closest is the general rural population. Around 80% of Chinese suicides are from the rural population, and the overall Chinese suicide rate is an order of magnitude bigger than the Foxconn suicide rate.
Southeast Asia has a very, very large problem with subsistence farmer suicides. Some programs such as restricting access to human-poisonous pesticides have helped where they were implemented, but yes, if you're worried about suicide, you should look at the rural areas, not at the factories.
Urbanization is a powerful force; it happens because people want to leave the rural life behind, and as it continues, it pushes the contrast ever more in favor of urban life; people move to the cities because of the opportunities, economy and culture there; and as they do so, they "carry" even more opportunities, economy and culture away from the rural areas to these cities.