About why use such a low bitrate - I believe ggwave is a bit more pleasant to the human ear, although this can be subjective I guess. I also think the transmission is quite reliable - at least this is true for the few devices that I am using. But I guess the main reason is when I started coding this, I had basically 0 knowledge about existing audio modulation schemes and today this hasn't changed much :-) I find it more fun to experiment this way, even though I am probably rediscovering basic knowledge or missing some well-known approaches or techniques in this field.