Right now there's absolutely no reason to encode lower than 320. In the future hopefully everything will be lossless because storage space is becoming less and less of an issue. From here the issues of production quality will matter more - there's no point having a lossless recording of a really poorly recorded and produced song or album. The "loudness war", along with a dozen other things, has more of an effect on the quality of music than 320 vs lossless. Next on the "why are you bothering" debate - 24/192!