This work analyzes the performance of the Reduced Precision Redundancy (RPR) error mitigation technique using the Fast Fourier Transform (FFT) as a case study. To this purpose, several configurations of an FFT IP design were implemented in FPGA using Reduced Precision TMR and tested under proton irradiation and fault injection. The cross-section, the sensitivity to Common-Mode Failures (CMFs) and the signal-to-noise ratio of these configurations were evaluated. The results of the radiation experiments and fault injection campaigns are in agreement and show that the Reduced Precision TMR technique may be used as an alternative to TMR if small errors can be tolerated, as it has a good performance in terms of error correction capabilities, area usage and sensitivity to critical errors.