backups? I version concerts as I build them, and save along the way... so... gignextfriday.1, then .2, then .3... so forth and so on?
failing that... I believe the channel strip settings are "in" the file itself, so right click on the file, and dive down into the contents... copy and paste the channel strip settings into another folder, then start MS again, and drag and drop these one by one into a new, blank concert and patches... its not a full recovery, but it's better than nothing.
Logic v9.1.8 (64-bit), MainStage v2.2.2 (64-bit), OSX v10.8.2
MacPro 8 core 24GB RAM, 2x 23" Cinema Display
MacMini i7, 16GB RAM
retina MacBookPro, 16 GB RAM
MacBook Pro, 8 GB RAM, MOTU 828, GlyphTech ext drive
MacBook Pro, 6 GB RAM