That said, I don't know what's going on with your Airplay's music streaming, but the bitrate of music is far below Netflix's. It shouldn't matter much though, I stream my desktop in nearly lagless 1080p to my MBP via Splashtop. The compression isn't really that bad.
According to this review[1] it won't be useful for the Google Chromecast: "Internally, the hardware supports 2.4GHz Wi-Fi 802.11, which isn't quite as nice as the dual-band Wi-Fi offered on Roku's Streaming Stick."
[1] http://reviews.cnet.com/digital-media-receivers/google-chrom...
But it's not the bitrate that matters so much -- it'll work perfect for 20 minutes, and then completely fail for 2, then come back perfectly again.
I think the issue with my wireless is I'm in the middle of Manhattan and there are 40 wi-fi networks I can see, so it's already a little tricky. But whenever I turn on my microwave, transmission completely drops. So it's basically anytime I or any neighbor in five directions turns on their microwave.
5ghz channel sounds like a great idea, unfortunately I can't figure out from any manuals or docs whether my Zeppelin Air supports 5ghz or not -- the official specifications and manual just say "supports Wi-Fi". [Edit: Googling forums suggests it only supports "g", not "n". So, no dice. Oh well.]
I don't think that is the typical experience.
Now if that device habitually drops the connections, or doesn't support video, it's a problem with the device, not the technology.
However, Netflix etc. work fine over wi-fi, because they're downloading and buffering the compressed stream itself, and then feeding that via the HDMI port to the TV.
Chromecast appears to be able to download the queued content over wi-fi, and then transmit via HDMI, which is a much more reliable way to go, given the state of wi-fi.