With a packs off T/O we could gain an extra 1000KGs, but it's not recommended at Quito as you would be above 10,000ft in only a few seconds, and the crew should really be wearing O2 masks.
I had a cpc failure out of Quito for Guayaquil in an MD-11, we were 12k to 14k in the time it took us to don oxy and go manual on cabin pressure. That approach and T/O is a BLAST!