We perform a likelihood analysis of the constraints from accelerator experiments and astrophysical observations on supersymmetric (SUSY) models with SU(5) boundary conditions on soft SUSY-breaking parameters at the GUT scale. The parameter space of the models studied has seven parameters: a universal gaugino mass m 1 / 2 , distinct masses for the scalar partners of matter fermions in five- and ten-dimensional representations of SU(5), m 5 and m 10 , and for the 5 and 5 ¯ Higgs representations m H u and m H d , a universal trilinear soft SUSY-breaking parameter A 0 , and the ratio of Higgs vevs tan β . In addition to previous constraints from direct sparticle searches, low-energy and flavour observables, we incorporate constraints based on preliminary results from 13 TeV LHC searches for jets + events and long-lived particles, as well as the latest PandaX-II and LUX searches for direct Dark Matter detection. In addition to previously identified mechanisms for bringing the supersymmetric relic density into the range allowed by cosmology, we identify a novel u ~ R / c ~ R - χ ~ 1 0 coannihilation mechanism that appears in the supersymmetric SU(5) GUT model and discuss the role of ν ~ τ coannihilation. We find complementarity between the prospects for direct Dark Matter detection and SUSY searches at the LHC.