Single-event (SE) performance of a variety of radiation-hardened by design (RHBD) flip-flop (FF) circuits is evaluated at the 7- and 5-nm bulk FinFET nodes. For a given RHBD technique, the 5-nm node design has an SE upset (SEU) cross-section an order of magnitude higher than that at the 7-nm node. Such an increase in SEU cross-section was not seen with the scaling of previous nodes. Simulations indicate that the increase in SEU cross-section is due to disproportionate changes in SE transient (SET) pulsewidths and sensitive areas after an ion strike. A figure-of-merit is proposed to quantify the efficacy of a given RHBD technique. RHBD FF designs are evaluated using this metric to show the efficacy of spatial and temporal RHBD techniques at the 7- and 5-nm technology nodes at both nominal and reduced supply voltage operations.