I went a little crazy:
This ErgoT project looks impressive!
With all the options you show with this...
http://geekhack.org/index.php?action=dlattach;topic=48718.0;attach=36220...you might as well have a totally separated true split option, also.
Besides the great ergonomic advantage, that would also make it easier
to store/pack for travel. And I think a cord is more robust & would
survive the stress/flex of travel better than a hinge or ball joint.
If the ball joint could be separated, you could have it both ways...
attached with a ball joint, or separated apart & using a long cord.
Or you could use a _detachable_ cord to connect the 2 halves
and choose which of 2 different types of cords to use...
Use a short thick semi-stiff/semi-flex cord to function
something like a ball joint when you do not need separation.
Use a long thin fully flexible cord for true split separation.