Confirming this is working.
- Setting hearthstone to new places works
- Can't seem to use zen pilgrimage after the first time
- Auction houses all work, however you're isolated from sending mail to anyone
- People can cast spells on you and you on them, eg heals/resses
- Both horde and alliance are "friendly"
- When you die in anywhere other than pandaria (only really tested EK though, and inside stockades) you res on your corpse as I'm guessing there are no valid GYs there. Pandaren GYs all appear to work normally though.
- You can get horde and alliance specific flight paths (at least in Pandaria)
Things I want to try,
- Forming a guild using pandas in the starting zone
Things that don't work,
- Can't queue for bgs, instances anything like that as you haven't chosen a faction
- All channels are empty (including trade) as you're technically on a different faction
- You chat in pandaren and no one can understand you in say (not sure if other pandas can who have chosen a faction)
- Can't whisper, mail, trade, invite anyone (again, another faction)
- Portals in the shrines aren't usable (paw'don alliance one does, honeydew isn't visible)
Once you've set your hearthstone to somewhere outside the starting area it doesn't look like you can get back to the starting zone, so yeah. Not really an issue unless you actually want to choose a faction :P