I don't remember saying that our site only needs CDN. If I did I apologize for the misunderstanding. However, we use the wordpress plugin called "Quick Cache" for caching (its faster, I'll leave you and others to debate that lol), we also use wincaches it has 4 other levels of caching and we had already done our own combining, minifying and serving of gzipped css/js files from Amazon cloudfont. (yes site will serve non-gziped files if user-agent cannot handle gzip found a simple way to have that done.)
So for now other than W3's VERY useful CDN the rest of the features are just bloat.