Not sure if this helps anyone with choppy audio but I have a workaround for my Bluetooth connection to my carkit...

After initiating a call with bluetooth already paired I simply switch back to handset and then once more to the headset using the blue button on the UI. This seems to correct other issues such as echoing on one side of the conversation too.

The only limitation I have found with this is that when the connection moves to another cell I need to repeat the procedure.