Agreed, by far the best guide I've found. My setup, based on that guide + some tweaks is at https://github.com/cbracken/mutt for anyone who might find another sample useful.
Yes, I was looking into the whole offline sync setup but I am a big fan of keeping a clean inbox so I just went with the current setup.
Also, one advantage of this is that changes are real-time which means that if I check the gmail app on my phone messages are correctly moved, marked as read etc.
It works great. Very fast, and it's nice to have a local backup of my email.