Open Source advantage
Consider this bug report for iTerm2, a terminal program for Mac OS X, where it panic’s Mac OS. The bug has been around for a while. There is no way you can actually check with Apple whether this issue has been resolved, is being worked on, will be resolved when, etc. That bug report by now contains a possible fix based on the Open Source version of the OS. In an open source OS this would be a) fixed by now by someone having the problem, b) probably be included in a release that has already shipped, and c) if not included, patchable in your local system by yourself.
The advantage of closed source is obviously blame allocation: It is their fault because I, the paying customer, say so. However, that is not much help on a thursday evening when struggling to make automated updates of 450 NanoStation M2’s work, with a laptop that crashes every hour.