I just posted a split testing tutorial for adsense I thought you all would like. After you start split testing adsense there are no more reasons for questions like "should I blend my ads more?" "does an affiliate ad work better here?" "does large or medium rectangle work better?" "does a link unit or ad block work better here?" All the answers are unique to your website and the only way to get an answer is by testing. To test you use split testing: http://www.45n5.com/permalink/how-to-split-test-your-adsense-for-higher-earnings.html
Sometimes it goes down, however you still know after using this which of the two is better and never need to guess. My current test has one channel at 5.56% and the other at 16.67% for the week. It's a nobrainer which one to choose.
Yep, ran a test on one of my sites this week - blended ads vs unblended. CTR dropped from 6% to 2% so quickly abandoned the test.
I see that your alexa traffic rank is 1, reviewme is $10,000 and you have 368k readers by feedburner (on the right bottom) ;-)