Good question Andy,
Googling vara qso , did bring back a few hits , one is a winlk p2p net , not really a qso as such , there is a IO vara group with ~ 500 members , posting there might help , look to be mostly usa based .. personally , I would suggest, vara-hf with chat module provides a near replication of the days of amtor , but, with considerable gain in s/n ,the other being the link remains in duplex , rather like packet , there is no master/slave .. also the link only sends data , when data is presented ..ie no data , it stop's when keying pauses ..little unnerving at first ..
Used to take 250 watts to work usa east coast on 7 with amtor , probably now 25w would suffice , though on link round test using the east coast Main kiwi web sdr , 5 watts has supported similar s/n mfsk link
CQ/QSO - sometimes the translation is a little askue , the comparison is pre coded messages , triggered by multiple pass , minimal 'on air' content , to actually transporting the full message content ..in live text , the system is most suited and robust , having spent hours in qso on 10 MHz during testing , a most unstable band
73 -Graham
g0nbd