What is the advantage of using OpenFeint or Game Center?

my company is developing an iOS and Android platform game which needs to track high scores and achievements. We use Unity 3D.

Is there a special advantage to using OpenFeint or Game Center for scoreboards, other than that they strip away the need for dedicated game web server / database? I read somewhere that the best practice is to design your own Facebook scoreboard server similar to Doodle Jump or Bejeweled Blitz, because it increases user engagement, but we're really not sure which option is the best for us.

Thanks!

Yes there are advantages of using OpenFient or GameCenter.

Advantage of GameCenter and OpenFient

1. Easy to use(this matters)
2. MultiPlayer Support(GameCenter)
3. Ability to integrate chat(OpenFient)
4. Offline support(OpenFient)
5. Cross Platform(OpenFient)
6. Thousands of game players (Using this services-())
7. Discovering friends how also play the same game(Great from user(game player) perspective)
8. Wider feature list(Both OpenFient and Gamecenter have great features) that are not very easy to implement
9. Saves Development time as well as cost(Matters to the developers on tight budget) 10.Unity has built in api for basic Game Center features 11.Important feature-Inbuilt Forums and Challenges(OpenFient)

This list could go on.

You can implement you own server and database for tracking achievements and highscores Still OpenFient as well as GameCenter will be better. Gamecenter support has been great after ios 4.0

I know the question states advantage for tracking highscore and achievements but i listed all the advantages just so you could clear idea about them.

You can set the dedicated server for tracking and achievements but just for this functions a server would be a overkill when you could use GameCenter or OpenFient

BTW just out of curiousity(I am an Unity Developer) what benefit are you planning to get using your own server and database(if you plan to) instead of using GameCenter or OpenFient