He is talking about MP3Pro, not MP3. I'm gonna try to not talk out my ass, but a 128k MP3Pro should sound like a 256k MP3 but only when the decoding device supports MP3Pro. If it doesn't (like the empeg doesn't), it will sound like a 128k MP3.

I personally use 320k CBR MP3s using LAME (converted from FLAC files). I use Exact Audio Copy to extract to FLAC.