On a personal note, it's a FAR better gauge of perceived loudness than simple RMS (or even the ridiculous DR figures quoted like the bible by audiophiles), which bears little resemblance to how the human ear perceives loudness and is better relegated to mathematical/technical/engineering measurements.
If Span Plus included 'resettable' integrated LUFS in some way, I'm pretty sure you'd guarantee many more sales, mine for certain!
