The parameter $\sigma$ is a kind of rollback depth threshold, except rollbacks $\ge \sigma$ are possible, yet still assured-finality-safe due to sanitization.
So, it is safe for $\sigma$ to be low, but are there performance or availability problems if it is too low?
Lower is nicer in that it lowers time-to-finality.
Discussion
The parameter $\sigma$ is a kind of rollback depth threshold, except rollbacks $\ge \sigma$ are possible, yet still assured-finality-safe due to sanitization.
So, it is safe for $\sigma$ to be low, but are there performance or availability problems if it is too low?
Lower is nicer in that it lowers time-to-finality.
Related
Related from ancient history: https://github.com/zcash/zcash/issues/3782