I recently launched my new site continentalspeculator.com and tested out virtually every caching method out there. I also tested out all the websites that purport to measure speed etc. I have come to the following conclusions:
1. Many of the speed testing sites are hokey at best...I don't trust them. I do trust my own eyes and stop watch while loading my own website.
2. My site loads rapidly without using one of the Big 3 Caching programs that are all the rave.
3. I am using EWWW Image Optimizer and Js Deliver - WordPress CDN Plugins.
4. I believe some of the big cache programs actually slow down wordpress
5. Of all the caching plugins out there, Hypercache combined with dbCache Reloaded produce far better results.
6. Much like switching off and on your router to clean speed up your network and clear out the garbage, I find that after making changes to my pages, that reloading WordPress 3.5.1 and then disabling and reloading both cache systems also speeds everything up...especially after installing other plugins.