I haven’t seen any workarounds or documentation on using them together. Generally, it’s not a good idea to implement two solutions that accomplish the same task, though I do know that mod_pagespeed works quite differently than Falcon.
-Brian
Mod Pagespeed is not a cache, mostly it rewrites jss, css, html and images aiming to reduce size and requests and so load page fasters on the browser. Falcon Engine serves static versions of most visited pages in the site, it does so via RewriteRules and aims to reduce server load during intense use so making the webserver more reliable.
What they have in common? They are kind of reverse proxies, they both gzip compress data and set VARY headers.
https://www.sonassi.com/help/magestack/understanding-cache-flow-when-using-pagespeed-and-varnish
But possibly it’s better not to use the two together. Falcon Engine add complexity and a lot of rewrite rules without adding much, especially with using a CDN. I understand that this plugin goal is to offer a fast and easy setup to caching to people that otherwise would be with hands empty.
