Macroscale actuation systems (power electronics) usually are not build with reversibility in mind. One exception are electric cars but industrial robots usually feature no energy recuperation. The necessity of energy recuperation creates novel challenges which will likely lead to novel designs.
As one goes down the size reversibility/recuperation becomes increasingly important. Especially down at the size of the specialized mechanosynthesis cores.
Introduction of energy recuperation will likely be introduced only in later more advanced higher stiffness nanosystems after the "foldamer era" where this becomes easier.
(TODO: Add some thoughts about specific designs.)