We recently switched to Amazon Cloudfront for static content. It seems that Cloudfront does HTTP 1.0 requests to the origin server (IIS 7.0) using the Via header. By default IIS 7.0 disables file compression for both these options (HTTP 1.0 and proxy (Via) requests), which can only be enabled for the entire server by setting the noCompressionForHttp10 and noCompressionForProxies to false in the applicationHost.config (http://msdn.microsoft.com/en-us/library/ms690689(v=vs.90).aspx).
My question is: what is the risk of enabling compression for HTTP 1.0 and proxy requests? Are these settings meanth for REALLY old browsers/proxies (eg. Internet Explorer 5) or does the problem exist in more recent browsers/proxies?