The server's return status is always multi-status (207). In my case my single property resulted in a conflict (409) embedded in the response. We should scan all of the response entities and only if they all have an OK status do we return true. We should also deprecate all of the current proppatch methods. We should create new proppatch methods which change the return type to Enumeration like propfind so that consumers can see what failed.
Search on the word buggy in XMLResponseMethodBase. May also want to special case proppatch.
NOTE: There are two places that are special cased.