I was thinking of paying the $99 fee for a dev account so I can DL Mountain Lion and use the airplay feature. This is the main reason I will be upgrading and was just curious if the feature is worth it? I'm using AirParrot now but its very choppy.
Also of course consider the throughput of your home router. If it's anything based on the 802.11N spec, it should be sufficient for AirPlay so long as there isn't any other major traffic going through it at any given time.