Stress-biased actuators, such as Rainbow and ThunderTM devices, offer enhanced displacement performance compared to unimorph and bimorph actuators. Quantifying the relative contributions of mechanics (layer thickness ratio) versus stress effects on actuator performance has proven difficult. In this paper, the importance of domain switching and altered domain configuration on actuator performance is considered. X-ray diffraction has been used to characterize the initial domain configuration in the surface region of the actuators, as well as the domain switching characteristics of the devices under moderate electric fields. Samples with different reduced layer thicknesses were fabricated to alter device stress state, and consequently, domain configuration and switching characteristics. Compared to poled polycrystalline ceramics of the same composition, Rainbow actuators display a slightly higher a-domain population in the surface region of the devices. Interestingly, despite the presence of comparatively large lateral tensile stresses in this region of the device, x-ray diffraction indicates these devices also display greater 90 degree(s) (a- to c-domain) switching, which contributes to the large displacement responses that are observed. The contribution of stress to the enhanced performance of Rainbow and ThunderTM devices is, thus, more accurately described as arising from a change in the initial domain configuration together with minimal suppression in the switching response under high lateral tensile stresses, rather than simply a stress-enhancement of domain switching. The effects of stress on the initial domain configuration and switching response were quantified to define the specific role of stress on the electromechanical response of the devices.