But you have 16 mirrored to 4 on main, right? Otherwise, how is SEQ on 4 seeing the traffic on 16? At any rate - it's working for you, so maybe the details don't matter.

Though, I'm curious why you say it's generating a bunch of unnecessary network traffic. It seems to me that the only system that would see more traffic than usual is the SEQ box itself. Sure, there will be higher load on the switch, but assuming the link to the secondary isn't saturated, I don't really see a problem with your setup.