Cygnus X1

Actually, LAME currently does not have an intensity stereo mode; unless the user specifies --ms, it always encodes in joint-stereo. There has been talk for some time about implementing intensity stereo in LAME 4.0 for bitrates <96kbps, but given MP3's inherent format limitations (scale factor issues, short blocks being too long for very sharp attacks, not allowing joint stereo switching within different bands, etc), I doubt it will make too much of a difference. Higher bitrates, like --preset extreme and --preset insane actually use --nssafejoint, which uses a stricter algorithm for switching between LR and MS frames. That being said, LAME's joint stereo mode is always lossless when done correctly, regardless of bitrate. I'm not even aware of any real, empirical tests done to prove failure on certain samples, which is a testament to its efficiency.