Yeah, it might be that if you log off without leaving the party first that you will be back at the beginning of the instance with the NON-LEADER toons. If so, that will make it a little easier in that you don't have to leave the group first.

However, I believe the leader will find himself at the same spot in the instance when he logs back on. At least that's what happened the last time I tried this. I'll experiment more this weekend to see if there is a better way to do it. Maybe you have to be logged off for some amount of time before logging back in.

I'm also pretty sure that you have to be outside the instance to reset it, so the main goal is to get your toons out of the instance the most efficient way that avoids having to run back out and fight respawns.