bluntforce - 4:30 am on Jun 26, 2012 (gmt 0)
Removed affiliate links from higher trafficked pages - signups dropped - rankings did not change. Replaced links today - waiting to see if there's any effect.
Can't help you due to above test. There's a link in this thread going to a late 2010 discussion about possible Google A/B type (or more complex) testing, it's worth a few re-readings.