RE: PATCH Draft

# Why is Accept-Patch required. Or what is it that makes Accept unsuitable here?

Accept is currently a request header and not a response header.
What's acceptable depends on the method as well as the URI.

For example

(request)
OPTIONS /example/buddies.xml HTTP/1.1
Host: www.example.com

(response)
Allow: GET, PUT, POST, PATCH, OPTIONS
Accept-PATCH: application/diff, application/diff+xml
Accept-PUT: application/xml
Accept-POST: application/vcard

Accept-POST might be useful for forms submission URIs, to 
determine whether multipart/form-data, URL encoded, or other
submission formats might be acceptable.