I maintain sites using both the older synchronous and newer asynchronous Google Analytics. I also personally as a matter of course block Google Analytics using

I maintain sites using both the older synchronous and newer asynchronous Google Analytics. I also personally as a matter of course block Google Analytics using a few adblock rules. As a user I have never experienced page breakage due to blocked analytics, and as a site maintainer I have witnessed that you simply don't get analytics information from those users. I've had clients freak because their Google ecommerce data doesn't add up, but in the end that information relies on trusting the client.