Pointman, real good points (no pun intended). While for me, I like formal methods, you are spot on when you say that your "ears" really have to get accustomed to things like cadence, regional grammar/idioms even the pace of speech. I admit that when I travel to Latin countries, I try to rely on the Spanish I learned formally a loooong time ago, but with little success, because of the reasons you outlined. It's a bit frustrating (you really have to go through a cycle of attempted conversation, correction, remember, repeat), which is why I am interested in how people learn foreign languages.
Thanks.