One of the fundamental problems with EMAS is, I am informed, that once it has been used in anger, it has to be replaced in its entirity. So, if an aircraft overruns and enters the EMAS area, after it has been removed, declared distances have to be recalculated and operations restricted until the EMAS is re-laid. This also places an obligation on the airport operator to hold spare EMAS systems in stock in order to facilitate a rapid resumption of normal operations. This comes at a cost, which some operators may not wish to bear - no finance departments enjoy shelling out for something that is hopefully not going to be used.
HB