iOS multiplayer game - what to use for the multiplayer part?

I'm developing a game for iOS that should include the multiplayer. It's not a turn-based, rather a real-time game. I know I can use some different approaches here:

• Game Center multiplayer (has matching and searching for matches, gives authentication out-of-the-box, additional are leaderboards and achievements)
• As far as I know, OpenFeint also includes some multiplayer helpers
• I can also write my own sever code, but woudn't it be reinventing the wheel? I'd also loose all the good stuff from GC...

Any suggestions here? What's the leading market solution, that doesn't take too much to integrate into a game; I'd like to be able to send short bits of data between players (player position + action taken) in a real time. Best would be to reduce the lag :)

personally, i think the easiest way to go is with gamecenter. it was pretty straightforward to integrate it into an existing game - i'd say it took 2-3 weeks. the main problems that we encountered were to do with the game simulation not being particularly suited to multiplayer, rather than anything to do with dealing with gamecenter.