Personally I think that you should opt out of the statistics on your development machines, at least in your debugging browser (Firefox) or your quick-add-content browser (Chrome) but not on your real-user-test-browser (IE).
The best way to do it is with the plugin that Google provide so that you never register on analytics, with your own site or anyone else's:
Google Analytics Opt-out Browser Add-on (BETA)
If you want to opt-out, download and install the add-on for your current web browser. The Google Analytics Opt-out Browser Add-on is available for Microsoft Internet Explorer, Google Chrome, Mozilla Firefox, Apple Safari and Opera.