I agree with Gaucho. I'm an Economy-class flyer and I try to avoid MIA, even if it means more hours cramped at the back of the plane. Not only the airport is awful but the pax on the MIA-EZE route are not the most educated bunch, and they can make the whole experience quite unpleasant. Nothing completely terrible, but usually JFK-EZE pax are more civilised. This applies to Economy, though. I wouldn't know about Business or First.
That said, if MIA is much cheaper than JFK then go for it.
I wouldn't worry about weather delays and cancellations in November.