I looked up the torque curves for both the 6.2l and the 7.3l and the 7.3 makes considerably more power in the lower RPM range than does the 6.2. They both peak up around the 4000 rpm range but the curve is much flatter for the 7.3 with considerable more torgue at 2000 rpm.
Having the torque in the 2000 to 3000 rpm range where we operate the engine most appears to me to be a big advantage.
