I would say it's far more difficult if you want to support the full range of capabilities that the Accept header supports. Accept can support more than a singl

I would say it's far more difficult if you want to support the full range of capabilities that the Accept header supports. Accept can support more than a single mime-type, and can also include priorities on each mime-type accepted. If you combine that with multiple clients, I think caching based upon that header would be pretty difficult (or you'd have to make some simplifying assumptions). Impossible? No, not really. Worthwhile? My opinion is no. I haven't seen the practical benefits of the content-negotiation approach over the URL approach, but I have seen the practical difficulties, so I'm convinced.