EPR is rather elegant but its a ratio, not a value. As for it being a "truer" measurement of thrust, only half convinced. Seems to me that fuel flow is the best for answering the question: how much thrust are the engines putting out. Fuel flow in lb or kg per hour will give you virtually the same indicated air speed at any indicated altitude, weight and configuration being constant. more reliable than either thrust or EPR. But problem there is fuel flow is never operationally limiting, whereas all kinds of temp or power limits expressed as N1 or EPR.