olympic dam project, page-16

Temperature is one factor - thermal conductivity of the rocks is another critical factor. There is no use in targeting hot rocks if the heat is not effectively insulated - essentially your heat resource naturally bleeds off to the surrounds. As far as I'm aware, such projects are viewed as technically feasible, but practically challenging & $$hungry. There is always risk with drilling deep holes. As for personnel, GRK look to be using the technical expertise of various organisations & contractors, apart from developing inhouse.
I do think buying into a spread of these emerging Geothermal coys is probably the way to go - I think PTR have runs on the board & have been developing their inhouse expertise for quite a while now - if I remember correctly they've had a lot of direct input from Adelaide Uni & the projects that studied heat generation & thermal insulation of sedimentary basins in their region of interest.
I also think that rather than seeing GRK & PTR as competing, that they might actually benefit from each others work - technically, politically & financially - they are both working to promote & develope an new emerging technology (in Australia anyway...).