In reply to nel.

Hi Nel, As I mentioned above Pound is NOT needed in this scenario, Nginx can used where Pound is used and then used after varnish as well.

So: Nginx -> Varnish -> Nginx -> PHP

From a site performance point of view this is a no brainer, you can enable SPDY out of the box, you can make full use of mod_pagespeed rather then just its non user specific aspects.

From a security stand point it's also more useful as you can utilise Naxsi or similar WAF on the front end, you also can route unwated traffic through to things like Fail2Ban. (you can do some of these with the above setup but not as effectively)

From a management point of view Pound is an extra thing to worry about and maintain.