I had experience with this product Page Speed on server mod_pagespeed in Apache. It's very nice at first, but can become buggy in the future, specially dealing with sessions and caching, you can have problems you didn't have before and start dealing with them, that was my experience 2 years ago.
Today I'm happy optimizing the code doing what needs to be done rather then using the plugin, it's a lot better to manage and don't have to deal with strange bugs.
Keep in mind if you put any plugin to handle your HTTP for optimization you'll have some type of problem when dealing with sessions and client-side caching one day or another.
Unless your product is all static you're fine.
Best Regards,