AFAIK the boundary layer mics pick up everything which is not good. The tracker array microphone should be good in theory, but it's expensive and you never know until you try. No one has reported on it.
The Amulet is still the clear winner. It's just nice to know that it'll never issue a command when you don't want it to. It's not nearly as cool as being able to do it hands free, but so far it's the only thing that really works for me. Hopefully I can squeeze more out of the Kinect at some point. Hopefully...
I just tried another test of the Kinect after your positive report. I am sitting about 9-10 feet from it. It's on top of my TV. I have a 5.0 sound system set up. When the music was off or very low it was working reasonably well, but not great. When I turned the music up loud, it was hopeless. I couldn't get it to turn down again, and it was issuing false commands etc. I turned the music down again, but then my wife got home and was doing dishes (open concept room) and again it was hopeless. This is with me just using the Kinect with VC as you would any other microphone. I'm not using any special code for the Kinect.
I wonder how long until Microsoft releases another driver pack and if they will make any improvements to the generic mic setup.