In fact it is very easy to use both even in the same application!
You can find a detailed explanation at this site:
http://www.apptite.be/tutorial_mixing_ads.php
But in-short the idea behind it is to:
- Create an iAd banner and an Admob banner in viewDidLoad
- Only the iAd banner gets registered
- When iAd fails Admob banner gets registered
- If iAd would become active again, the Admob banner will disappear
It even uses a sliding effect to hide and show the advertisements in the bottom of the screen.
So far I can't give a correct number on the revenue, but I can say that the fill rate for iAd is around 30% and for Admob around 95%
Hope this helps you out!
Regards,
Luc