We investigate the role of various structural nonidealities on the performance of armchair-edge graphenenanoribbonfield effect transistors (GNRFETs). Our results show that edge roughness dilutes the chirality dependence often predicted by theory but absent experimentally. Instead, GNRs are classifiable into wide (semimetallic) versus narrow (semiconducting) strips, defining thereby the building blocks for wide-narrow-wide all-graphene devices and interconnects. Small bandgaps limit drain bias at the expense of band-to-band tunneling in GNRFETs. We outline the relation between device performance metrics and nonidealities such as width modulation, width dislocations and surface step, and nonideality parameters such as roughness amplitude and correlation length.