Thanks for the many replies...
We would generally be connecting stranded individual motor leads which do not have lugs on them. It would be nice if the connector were quick to attach, yet safe.
I am trying to avoid spring clips at all costs. Even heavy duty welding type clamps are just ugly. And at 230 or 460 dc or 480 AC, I really don't like the idea of the things coming loose!
The idea of the split bolt connector brazed to busbar is interesting and might work out. A dedicated wrench could be chained nearby to keep it handy. The Marathon style insulated terminal block is probably safer, and I could chain a T-handle allen wrench nearby. We could also install the finger guard covers, and drill small access holes for the allen wrench.
The idea of the air cylinders is pretty clever! Maybe we don't need it THAT convenient

I think you would still need some sort of mechanical advantage to get adequate clamping force. At hundreds of amps, I think need it tight.
The idea of the "cam over" fasteners is worth investigating... if I could find a cam over that would fit into an Ilsco style lug or Marathon terminal block, or a custom made block, it could eliminate the need for a tool to make the connection.