I don't remember the URL (sorry) but I saw something recently talking about Facebook's queueing approach for requests being FIFO under normal load and LIFO when overloaded, so that under an overload state you serve the number of requests you -can- serve reasonably quickly rather than -everything- timing out.

For node's situation that sounds probably workable but I think a lot of the time I'd prefer to send periodic keepalives to the idle pool connections. However, you can't exactly bake -that- into the runtime so I can see their argument and perhaps the best thing would be "both, plus periodically do a clean shutdown on excess pool members until you need them again."