Logic Soft Errors caused by radiation are a major concern when working with circuits that need to operate in harsh environments, such as space or avionics applications, where soft errors are traditionally referred as Single Event Effects. In this paper, system knowledge-based hardening techniques using recursive structures for the implementation of moving average filters that provide protection against Single Event Upsets are evaluated through two fault injection systems based on simulation and emulation respectively. Fault injection campaigns show that system knowledge-based redundancy techniques can achieve the same level of dependability as standard redundancy techniques, such as Triple Modular Redundancy, while having optimal cost.