I was part of a research group that used the Mini-Cog briefly but had to switch to the MoCA, since the Mini-Cog seemed to be only sensitive to frank dementia (and not MCI or early dementia). If you need any kind of variability, use the MoCA or MMSE -- the MoCA is more reliant upon frontal-attentional networks and therefore will be more sensitive for all-cause dementia (especially subcortical/vascular causes). Good luck!