Mutt, I'm happy to see that I have a fellow traveller in applying this conservative approach...
The said flight was indeed one of the early B747s, loaded to the gunnals for a Haj flight direct to home.
Payload penaltys of the order of 3,000 Kg are indeed significant, but I sleep better at night knowing that I've delivered my end users (the pilots) with information which errs on the side of safety, presumably you do too
Now that most of our B777 ops are based upon performance calculations derived from the EFB OPT, Heaven only knows what "precautionary" measures the programmers have incorporated......probably none!
BTW, welcome to the world of unbalanced field operations, happens to the best of us.
Regards,
Old Smokey