Hi Richard,
I haven't done site/ranking performance comparisons between using vs. not using Google Analytics.
But I've heard from so many sources (too many, actually. I wish I remembered all the links) that it's a very bad idea to have Google Analytics installed. I personally have stopped using Google Analytics as well. I'm now using an open source analytics script that's hosted on our own server. You can download the script from
www.piwik.org . It's awesome. It even has real time tracking as well.
Anyway, there's a post written on our beloved Warrior Forum which explains the dangers of using Google Analytics. Thankfully I have the link saved...here it is:
haha, funny - how google analytics could be 'hurting' you...
I bet after reading that thread, you'll say to yourself "wow, that really justifies my feeling wary and not good in using Google Analytics!"
By the way, it's also been advised everywhere, that using the Google Webmaster Tools is also not a good idea.........