Some Kingston SSDs allow you to manage over-provisioning (i.e. to choose the capacity-endurance tradeoff) by using a manufacturer-provided software tool.
This mod (I only just skimmed the post) provides a longer life not by using the cells less often (or keeping more in reserve), but by extending each cells life by decreasing the tolerance of charge needed to store the state of the cell, but in return decreasing the bits that can be stored in the cell so decreasing the capacity.