Multi-player server for iPhone application, using device as socket server

I'm working on a multiplayer iPhone application that allows up to 6 users to connect and play in "real time." I've been looking at hosted and non-hosted socket servers (SmartFox, ElectroServer, Photon/Neutron, ProjectDarkstar) and I'm wondering if anyone has any recommendations for services or implementation? Anyone have any idea of what a game like Zynga's Live Poker uses for this type of functionality or what kind of hardware you might need?

Some sub-questions:

1. The ga开发者_开发问答me is turn-based. Would it make more sense to use AMF and poll a server or should I go for the socket-based route? My current concern is concurrent connection limits and hosting costs.

2. Is it possible to "broadcast" a device as a socket server? i.e. once I get all my players connected, could I allocate one of the 6 devices to be a socket server and push all communication through that device? Would that be crazy? That would get around concurrency issues and I'd only need to rely on the socket server service as a lobby for the initial connection. The allocated user would stay connected to facilitate game to server communication.

1.

It's much easier to use polling, and since the game is turn based you could poll at a relatively slow rate (perhaps a couple of seconds), which means less battery drain. That said, using sockets or persistent HTTP connections would be a slicker way of doing it (and much more work). These two questions might be of interest:

How do I create a chat server that is not driven by polling?

COMET (server push to client) on iPhone

I don't know why you would use AMF. Why not JSON? Or maybe HessianKit?

2. It makes a lot of sense to designate one of the devices as a server. Having a completely decentralized network of game clients that need to synchronize is a very hard task. Again, since your game is turn based, which doesn't require perfect real-time synchronization, you don't have to worry that having centralized state will introduce more latency.

If you intend for users to play over a local network, you should consider using GameKit.