Yes , Quite agree Andy ,
The vara modem started years before it broke the surface , in many variations, the fully odfm version was and remains radical , the mfsk front end to the HF version, signalled the limitations to psk modulation .. perhaps echoing the MT63 , progression to Olivia in terms of s/n
In reality , 'we' as in data mode users are now 10 years behind the times , Ros HF , introduced , 'efficient use of bandwidth' whilst maintaining QSO integrity and equal channel access for users at minimal s/n levels .
To day , as already commented , non coexisting transmission formats are spreading along the dial
Only need to observe the psk-map 11 meter band , when there is a opening , to observe , the traffic level
supported in a single voice channel , by non ham users , demonstrating the validity of the designe .. and the far sightedness of the SS Trial group , who also came under fire ,