The benefit of a Open Source casino is the fact that the code can be scrutinized to see if the games are profitably fair and people would be more willing to use these casinos, because they would trust them more than casinos that are using proprietary code.
The disadvantages of Open Source casinos would be that it would have to be flawless. The hackers will have a feast if they can find a exploit in the code, because it is out there for everyone to see.
Good luck with the project.
![Wink](https://bitcointalk.org/Smileys/default/wink.gif)