For starters, how would we know? The software in question is closed-source and has spotty docs as best - and more importantly: your trust in a software is something that only you can establish for yourself, irregardless if whatever number of people on the internet claim the product trustworthy.

Appelbaum on FileVault(1) in 2006: http://events.ccc.de/congress/2006/Fahrplan/attachments/1244...