[mstade]

Arguable. At least an unknown header is likely to just be ignored, whereas a URL that’s changed to update the version will at best cause 404s, unless you keep the old URLs around. If those URLs are still recognized, but routed to the later version anyway then that’s just as bad as using an unrecognized (and likely ignored) header.

In any case, what you’re saying is the point I was trying to make in the latter part of my post. However a typo (or rather, a missing word: “no”) unfortunately changed my meaning entirely. :o(

It should’ve read:

> (to my knowledge there’s no Accept-Version header)

Oops. My apologies for the confusion.