Assuming you're using AirPlay Mirroring (besides iTunes, I can only find to Beamer and HUDTube to send video directly to an Apple TV from a Mac--neither of which help here) the main loss will be frame rate. I can tell when using both Watch on Slingbox.com and the older SlingPlayer for OS X software that the frame rate isn't as good as if I had a (wired) HDMI connection.
However this doesn't seem to be a failing of the Slingbox. It seems to be a limitation of AirPlay Mirroring--when I watch other video sources (e.g. CBS on Demand, ESPN3) via AirPlay Mirroring I see the same lower frame rate. Strangely, AirPlay from an iOS device might give better results since there's no mirroring occurring--the stream is being processed and sent directly to the Apple TV. I should compare the two.
If only the iPhone app has functioning AirPlay, it's counter to Sling Media's press release on the subject:
And finally, Sling Media is pleased to formally announce AirPlay support for SlingPlayer Mobile for iPhone and iPad. This feature gives Apple TV customers the ability to watch their home TV on a second TV inside the home (without needing an additional set top box) or on a remote TV. Slingbox 500, Slingbox 350, Slingbox PRO-HD and Slingbox SOLO customers can take advantage of this fully updated and supported feature.
Results with current-generation Apple TV with third generation Apple TV and Slingbox 350:
- AirPlay via OS X 10.9 "Mavericks" and Late 2013 13" Retina MacBook Pro: High resolution picture, but lower FPS
- AirPlay via iPhone 5s: Lower resolution picture, but higher FPS
- AirPlay Mirroring via iPhone 5s: Even lower resolution picture, medium FPS
Leads me to these conclusions:
- If smoothness is important (i.e. sports programming) use AirPlay via iOS
- If sharpness is important, AirPlay from OS X should suffice
- If smoothness and sharpness is important, wire the computer to the TV
It appears AirPlay from OS X prioritizes resolution over FPS, while AirPlay from iOS prioritizes FPS over resolution.