And ogg and m4a and opus and so many more.
I have an ipod 6th gen runnung rockbox. Its great. If the harddrive dies I'll replace it with sd-cards and still keep uaing it.
Rockbox is cool, I just wish it was able to replace the base system without touching the UI. Something about it just feels off on an iPod. Even supposedly iPod-accurate themes just feel uncanny.
It's a shame rockbox doesn't support video playback though.
How is stability for you? My 7th gen with about 750gb is pretty unstable, mostly I have a lot of difficulty transferring since the iPod crashes 15gb in all the time.