Also check out Application Insights on Visual Studio Online. Currently what is exposed in the Azure Portal is a tiny bit of its capability.
You can instrument your code to expose any metrics you desire. Including A/B testing. ie: Exactly what did they click on & how long did they look prior to clicking. Avg Price of each order etc.
It also gives you complete stack trace & can link it to a specific build of your code to help step thru debug your production code even if your developers are working on a much later build.