MP3 truly is junk. The only thing that can help are some of the finer recordings of MP3's, typically done on a "covert" + "professional" level. Even then, typically those files are the types you can only get in that format as you'd never find them in the US (hard to find European or Arab/Middle Eastern tracks).
But anything that you have on redbook or that you can download via .FLAC or .WAV, there is NO reason to go to an MP3 to save space. 2tb drives are cheap - go get some.
