You ever wonder why no one does Orvr? Does it make you mad when you see so many players guarding the mailbox? Do you wish they would come out, and help attack, or defend?
The solution is really easy. I am not kidding. On Dark Crag no one ever, and I mean no one ever felt like an outsider. Yes our guild had our one private warband, but the officers of our guild were required to run open warbands. If you needed a warband you knew you could get into one. That is why we easily fielded 3-4 warbands a night that worked together.
We weren't elitist. We didn't run a gear score, or tell you that you suck, or laugh at you. Everyone was treated the same. We are fighting for the same cause right? We didn't have one guild/alliance warband negating what the other guild/alliance warband did. We worked together like a well oiled machine.
It is why on Dark Crag we reached the city every night before they made it easy. I remember on my old server Magnus we never got to the city once before the server closed a year later. There were egos everywhere. This guild leader hated this guild leader, and so on.
You know what happens when you start leaving people out? They turn against you. They stand in warcamps, or they log on their destro alts and ruin your day. They log into the Undercroft, and run suicide missions into Destro to keep you from reaching stage 2. They let destro spawn camp them in a city instance to give them VP.
Another thing is we offered our vent to anyone. It was a 200 man vent. Anyone was allowed to log in. It wasn't a bunch of 12 year olds yapping either. Most people were amazed at how organized, and smooth our zerg guild ran. Of course the vent had destro spies in it, but that is what made it fun when we rolled over them again, and again.
So if you want players to do Orvr start opening up your warbands. Quit trying to be elitist in a team/faction based game. If you want your private warband than at least have a few officers start an open warband. You would be amazed at how great it works, and eventually how people want to join your guild. You don't have to try to spam recruit guys you see with no guild tag. Players come in droves every day.