Tyrbiter n3sam I think because M17 is intending to use codec2 speech coding and there are not yet any commercially available implementations like the AMBE-in-a-chip that the openSPOT3 and 4 use. You also have to consider how the frame/slot timing is done.
SP5WWP With commercially available M17 radios, such as the CS7000, I have no clue why the mode is still omitted in your hardware.