Well, I don't care if the Echo can transmit BT or not, because the Echo is mono, not stereo, So, unless that could be rectified as well, what is the point? Jeeze, just get and use a Dot (when available again).
All this "stressing" over what the Echo can and cannot do. I am just happy the Dot exists and I have one. I think those saying the guts of the Echo and the Dot are same are "shooting from the hip". Only Amazon knows for sure, and they are not telling.