MPGH isnt 100% for hacks.. they do modding n shit if im not mistaken too.
As for the overlay, i feel it could end up getting you in trouble in some way, but i personally dont see anything wrong with it, its the same as alt tabbing and using a map, as it doesnt add your location or anything. just saves you the trouble of alt tabbing. and removes the risk.
Well, the fact that he is registered on such a site is interesting, but until he gets VAC banned I'm willing to give him the benefit of the doubt.