I think it's a fine idea if it doesn't cause too many Dev headaches.
The dual box complaint might be if someone has one account in the Hive or Abyss, and any other accounts are doing stuff outside the map. Allows someone to "save" a spot, but they're still doing stuff. Though one would think they would be more responsive than someone who parked and went to make dinner.
Looking at the charts, doesn't look like Excelsior has exceeded the 1500 players at a time for the last week, so as long as they don't multi in the raid zones themselves.