Replace Code Igniter's database layer with Doctrine 2

[eluser]Funny Bunny[/eluser]
Hello,

Coming from a Java background I pleasantly surprised at the way Doctrine 2 integrates with CI and especially the way it integrates with Code Igniter. So surprised that I wondered how hard it would be to replace Code Igniter's database layer with Doctrine, both for internal framework use (thinking database backed Sessions) and external use.

Has anyone tried this? What would be the pros and cons?