What I mean is, currently when you enable Airplay from inside the Slingplayer app for iPad it still appears that the stream goes first to the iPad then wirelessly to the Apple TV, which means it is always going to be prone to any wifi problems you might experience from time to time.
However some apps hand off the connection to the Apple TV which means if the ATV is connected via ethernet you might get a more reliable stream, plus it'll likely you less of the iPad's battery.
I've verified this with my router's diagnostics pages - with Slingplayer iPad Airplay the data is still going to my iPad. With other iPad apps I see the data stop going to the iPad and then go to the ATV directly. I believe this is also the case with the Roku Slingplayer app where there is proper hand off to the Roku.