I got a NEW Fluval 304 about two months ago, I love it. The older ones had some issues, but this new design is great. I have mine in my living room under the tank and can't hear it at all. The media baskets are great, you can take a few out to alternately clean them and leave the others alone. I have a 46gal bowfront if it matters.
As for replacing the media, I mainly just have biological media, and the sponges. Rinse them and that is all you need to do. You can use carbon if you like, and it still has room for other stuff.