I'm surprised you had so much trouble with your BT headset and iChat. I paired by Jabra BT300 headset as soon as the new Bluetooth software came out and I haven't had much trouble. I don't have to re-pair and iChat conversations sound great with no echo to speak of. Listening to music using the headset doesn't sound very good, but that's to be expected. Speech recognition also works as good (or bad, still working on my American accent so my Mac will understand me better) as with the internal microphone.
The only problem I had was that an older version of iChat had a hard time switching and remembering audio in/out settings.
A tip for anyone using iChat's audio chat feature without a Bluetooth headset: by using some regular headphones the Mac won't be hearing it's own speaker output back through the microphone. This allows the sound to flow in both directions at the same time, making everything sound much better.