from my testing.. 132k atrac3 is atleast as good as 192kbps mp3, probably more like 256.

I recently purchased a NetMD for portable use on the bus.. and recording at LP2 (2 CD's per minidisc) which is something like 92kbps.. still beats mp3 by a long shot.. still comparable to 192kbps. several other sites attest to that...

as far as hackability.. atrac is just like mp3, but the encoder/decoder are 100% proprietary.. and i have yet to see any freNIX stuff for it.. sony is such a bunch of assholes that way.