Do I need the optional circuit breakers?

If the power feed is protected upstream, by an appropriately sized overcurrent protection device, an input circuit breaker is not required. If the output is feeding a distribution panel with a properly sized main circuit breaker, the output breaker is not required. With all of that said, having the circuit breakers located at the UPS adds an extra disconnect point, centralized at the UPS for quick and easy bypass function for repairs or maintenance. If paralleling UPS systems, both systems should be equipped with the optional circuit breakers.