I have a 3rd gen ipad that I would like to use for presentations. It looks like keynote will only use the actual Mirror option and will try to optimize the resolution of the Airplay mirroring for whatever the output device is.
Let me explain:
1. ipad 3rd Gen using Keynote
2. Apple TV (2nd Gen), with the 720p output
3. Panasonic projector that goes up to 1280x resoution (full 720p)
However, it seems like the ipad will only work with the 1024x768 resolution in keynote.