However, coffee and sugar have similar base prices ($45k vs $35) so if coffee price starts going down and sugar is scarce, sugar production will take over fairly quickly. If sugar price then starts going down and coffee is getting scarce, production will switch back to coffee. End result is that demand for wool should be pretty stable and the local market should be able to absorb both products fairly well until the railway arrives in town (production in this case was only 1 wool to 1 of product, with maximum production set at 1 load). It seems to work.
However, if you are in a more common situation where you really want one building to engage both production chains you end up with the obvious problem: it won't work like that most of the time. It will either produce lots of something and hardly any of the other thing, or it will do a half-arsed job of producing both. The 1.06 Furnace is notorious for this sort of behaviour.
