An idea. What about using a combination of the two? So far, the story on iAds is that the fill rate is very low. Apple suggests moving the BannerView off-screen when the ad request is not filled (great idea). After moving the BannerView off-screen, why not move an AdMob ad into the void. Not sure if mixing ad platforms would cause poor user experience, but it might be worth considering.
Just a thought.
Andrew
