Whew, I have just spent an inordinate amount of time responding to various dangling comment threads. Despite my best efforts, I fear I may have left some points or questions unanswered. If I did, I apologize. If there's anything you'd like me to respond to that I haven't, please post it in the comments section of this post. (If you're picking up a thread from another post, please include a link.)
My thanks to Luke and Publius for ongoing lively discussions!