Just read an interesting post...
some publishers reported drop in EPC/CPC from around 0.3 to 0.03 gradually (which probably is due to smart pricing, the CPC drop with low conversion rate...). However, after switch the ads to YPN (yahoo publisher network) for a few weeks and back to adsense (due to bad targeting in YPN), The adsense CPC moved back to 0.3 !!
Does this mean the conversion statistic will be gone for a few weeks after you stopped serving adsense ads ? and thus, the smart pricing "penalty" had to start all over again ?