iTunes Library Manager and iTunes Match
I have received a handful of disparate reports regarding issues running iTunes Library Manager with iTunes 10.5.1. In short, iTLM will not display backed-up libraries correctly and in one scenario crashes when attempting to Save or Load.
I am currently investigating these issues, no doubt precipitated by changes in iTunes 10.5.1 file management. Under the circumstance, I cannot recommend using iTunes Library Manager if you also intend on using iTunes Match.