I've dumped 60+ tonnoes on the 777 once some 8 years back. The fuel gushed out from the nozzle like water from a fire hose. We were on steady radar heading and descending from a rather high altitude. The fume smell in the cabin is actually fairly strong. I would say flying close to the trail of it would be very unpleasent. Dumping in a race track hold would ( I reckon) be dumb.