I second the notion of making a new discussion on this, because I have words to say.
JackTheBandit seems busy, 8bit. Could you start this discussion. You have "words to say." I'd like to hear them. humanodon, you're multilingual, right? so you might have words as well. Which [human] languages seem preferable for communicating certain ideas?
In a recent discussion with wasoxygen, I mentioned that my multilingual grandfather used Polish for swearing - specifically if he was beating someone in chess, he'd call them a donkey in Polish. I wish I could have asked him this queson. -- but to "communicate" you pretty much have to speak in a language the person in front of you will understand. Multilingual authors might have much to say on a preferred language.
I am, though I wouldn't say I speak anything other than English fluently. I can get by fairly well in a few languages though. Certainly well enough to buy things (like beer!) and flirt with locals. As for higher concepts, perhaps there are particular grammars or vocabularies that express certain concepts more clearly than in another system, but that would be hard to compare and quantify. As for the thing with your grandfather swearing, was he Polish? I ask because linguists have long observed that people tend to curse in their L2 (their acquired language/languages) even if they don't in their L1 (mother tongue).