Well I'm already getting 25k/hr trio boxing (or rather, 2-boxing and the 3rd character leeching). If I can find a camp with more mobs, that can easily go over 30k/hr. That's already a pretty good amount; I don't know why people's default knee-jerk reaction is to whine about everything, it's not that bad. It's about the same as 8-10k/hr merit pts back in the day.
And I don't seem to be getting a reduction going from 1 person to 3 people, but I'm fighting weaker mobs (106-111 per kill)