I think it's also a good idea to wait a month or so after release. What's the rush? Let the first production runs go through and work out the kinks. So far I have heard some reports of screen issues on some 5s models. With a new and unusual part like the fingerprint sensor I'd rather wait a bit.
Personally, my rush was that I needed a device with an A7 in it for testing purposes. If it wasn't for that, I'd be right there with you and would have just ordered online and waited.
It will be for almost everybody, as long as you have someone somewhere with a 5S to use for a sanity check before you ship.
In my case, there was some code dealing with low-level stack walking and such that really needed the actual hardware in hand. Not a common case, to be sure.
