Ok, I *think* I've sorted the ArmA1 issue with teamswitch and moving groups. To recap: if you were the leader of a group and teamswitched out, the group would simply stop and freeze.
The real solution was here, by Wolfrug:
http://www.ofpec.com/forum/index.php?topic=30086.0But there was no effective (or at least easy) way of catching when the player teamswitched, until A2, with onTeamSwitch.
http://community.bistudio.com/wiki/onTeamSwitchAnyway, I put this into the init of a SIMPLE simple mission.
onTeamSwitch "selectPlayer (leader _from); {_x doFollow leader _from} foreach units _from; selectPlayer _to;";
It looks like it works, at least with pre-set (in editor) waypoints. Haven't played with it in terms of scripted waypoints or sending orders then teamswitching out.
(Also, I don't think the semicolon inside the quotes is necessary.)
This may not be the "real" solution, but it is a step, methinks.