Re:There is no answer, it depends on what you want (Score 1)

Trust goes with every "scientific" invention - I trust newton's laws because those laws have been tested against nature several times. In a similar manner, in open source, several different programmers have tested a piece of a code for holes - if there are still holes, those are the not-so-obvious ones (like what happened lately with DNS/bind). For closed software, unfortunately, it will be only the 30-40 team members that test the code (in the best case scenario). My 2 cents.