netmeg - 3:33 am on Nov 20, 2012 (gmt 0)
FWIW I have migrated ecommerce sites with thousands of 301 redirects in htaccess without issue.
But phranque's idea is probably the most efficient.
AdSense is contextual (more or less) which means the bots have to be able to properly crawl your URLs. You could test them in GWT to see what they look like to Googlebot.
But to avoid problems with AdSense AND in the organic SERPs, you should fix them once and for all.