I believe everyone will agree to use a fuse close to/at each battery to give protection in case a wire is shorted somewhere along it's length, etc.
The OP (in his link) mentions this, but also indicated them being eliminated in his drawings to keep it simple.

As to a pin, ring terminal, fork terminal, soldering a boot at the open end can help with connectivity over time. Just don't wick solder up past the other end of the crimp to preclude making a stress point.

Wiring should also be fine stranded so it's flexible, solid wire can fatigue fail over time due to work hardening of copper with even minor bending.