Anyone have success with it? I'd be surprised if that were a different type of teleport. EDIT: though maybe I just messed up the teleport position when I tried it.
On PC, the zz_dae_debug menu doesn't seem to do the same type of party teleport as the Gather Party horn does. Maybe I'm misremembering when you see him first (Act 2?). The Gather Party trick doesn't seem to work mid-Act 1, on the Viscount's office door. I couldn't get the second half of logitechSDAZ's skip to repeat on Blackpowder Promise - zoning out at the exact right instant - but I think my timing just sucks. Place your main character right,and you'll hop right over stuff. It looks like the teleport that happens after a Gather Party happens ignores boundaries.
Confirm the same party, and the party teleports to its default positions behind the main character.
Hold position on your main character, with his back facing the gate, Then, run one of the other players to the Gather Party horn. It's possible to hop the Arishok's gate by abusing the Gather Party horn just outside the gate in the Docks.