When we evaluated cachefly last year, setting headers was not possible -- the files were just served with etags and whatever defaults cachefly servers had. You

When we evaluated cachefly last year, setting headers was not possible -- the files were just served with etags and whatever defaults cachefly servers had. You also had to upload files manually, no pulling files from origin servers automatically. No custom headers was an absolute deal-breaker for static images, css, js. If you can't set an expires header, you've probably undone most of the good of distributing the content around the globe anyway.