Basically the two issues I've seen are the following without Airgroup.
I have 2 networks (doesn't matter which they are connected to)
- an 802.1x network
- a WPA2 password protected network.
iPad 2's with iOS 7.0.x will briefly connect to a nearby Apple TV. The image will mirror then stop within 10 seconds. I've heard this outside of Aruba networks as well. I can mirror my iPhone to that same Apple TV and it works fine.
As for the 802.1x issues on the iPad 2. It will allow me to authenticate with the iPad 2 then simply stop loading web pages.
I have only seen this on iPad 2's. I think it is a hardware/driver issue with them to be honest. We have a couple hundred iPad mini's, iPad Gen 3/4, iPhones, etc, that do not see any issues with the 802.1x or Airplay issues.