Hi Chad,
All I can say is making content support translations requires a more complicated db schema and adds a lot of complexity to any sql logic. That is why I have avoided it and recommend the multi site approach, it keeps things much simpler at the implementation level.
In your own custom feature you can do whatever you like, but you are faced with the same challenge that will require a lot more complexity. Nothing in mojoPortal limits you in your custom feature. Even if you have a specific culture set for the site, all that does is set the culture of the executing thread and you can reset it in your own feature to whatever you want based on a dropdown list of cultures or a cookie (set by a dropdown list or link click) or something. Of course setting the thread culture only affects string formatting and which resource files are used, you would have to figure out your own logic to store and retrieve culture specific content from the database, or a default culture if nothing exists for the requested culture. But again you will have to figure out the best way to structure your schema in order to efficiently retrieve the right data. It will add a lot of complexity to your app but it can be done.
Hope that helps,
Joe