Couldnt agree more, and interestingly the load control computer will normally aim for an optimum mac setting of say 20% in this case which would negate the performance calculation setting of 25%.
Moreover it is not uncommon for the crew to receive a higher TOW on the loadsheet than on the FPL, and to therefore ask for a revised TOP calculation after the aircraft has been loaded and prior to pushback, changing the MAC setting at this point should be done with caution especially as stated in my last post a "magic" 700kgs or so of extra weight can be carried.....