No! Headers are much worse. There is nothing in an API response that tells you in a standard way how to set headers, but there is something that tells you how to follow links (URLs). Accept-version is a non standard header, not defined in the http spec so definitely that is not restful - how do you know if the site supports it or what the version numbers are? You have to hard code in the client!
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)
