Be careful with OSX
The 7 days I did have my Cowon was amazing, really smooth O/S, fantastic codec support including DivX and FLAC. The features they had built in were stunning, the touch screen was so responsive and the sound from the Cowon was out of this world, beat the crap out of iPod piss-poor excuse for audio. I was using a pair of Etymotic Research ER4Ps, the sound was like nothing I have ever heard before, it was just stunning. Take it from someone who has shot their hearing to pieces at loud metal gigs.
I really liked Cowon stuff but the J3 I had did not play nice with my Mac. OSX would simply see the FAT32 filesystem, write to it and corrupt it, the J3 would see the corrupt files and format itself wiping out my media. It is an acknowledged problem by Cowon when trying to use some Cowon units with OSX, you can get problems.
When Cowon and OSX play nice together, I will certainly go back to Cowon.