Are there any other disadvantages of this approach other than the problem with "Service Appliances"? Many REST APIs rely on HTTP headers for other things - do "Service Appliances" only remove non-standard headers?
I once saw a significant uptick in users being unable to use an AJAX application because a developer "fixed" the RPC stuff to sent Content-Type: application/json headers instead of claiming to be text/html.
E.g. if you are programming GData client, it suggest you to add version info (i.e. GData-Version: X.0 ) in the request header.
http://code.google.com/intl/zh-TW/apis/gdata/docs/developers...