Okay, so coming from a user of CI 2.0 mind you and using integrated smarty templates with it, I would have to say after using even a micro-framework say silex, I could build a much better enterprise application with modern php5.3/5 features than i can with CI. The major problem is it feels really dirty to include/require statements with CI. Also to build re-usable code within the confines of their existing library system you have to build all your constructors with a single $param argument. The models are junk since they are really just a place to store organized function calls. Their database abstraction is an abomination. Generally the only thing good about CI is that you can break up your source into a marginally logical fashion which can it improves maintainability.
Now as for this application being written in Code Igniter? I don't really see it as a problem since it means it will be easier for lesser experienced dev to pick up and run with the ball. In time they will learn it's major deficiencies and they will move on. But i think there is room for improvement, in fact I think this would be a great project to port to another maybe more robust framework and is a good project for learning new framework translations.
I will say however that the author wanting to rewrite a product like this in nodejs is really only going to make something like this more inherently difficult to maintain since javascript code tends to get more complicated than your typical java / php / python app as it grows. Granted you do have js at your finger tips it is still largely un-tested on massive scale for large application development. It however has shown great promise for handling extreme traffic in terms of concurrency, but it handles it mostly by using async libraries which pile everything into queues of some sort some where. So your code is littered with async callbacks everywhere. Anyways.. Not only that, but the biggest problem of all is the inability to intelligently step through your code with some kind of IDE beyond using a browser-base debuger such as webkit inspector or the online IDE cloud 9.
I don't hate nodejs. I just think people are jumping on the band wagon way too quickly for server-side hosting. For websockets it's a great solution, I just don't like seeing it as "the only solution" for some peoples projects. I'd rather see a more hybrid approach.