All I can report, is what I experienced. When we turned my QNX system off, six years after go-live, it had never been rebooted. Hardware was nothing special, uptime of over six years. But then the QNX kernel is only 16k, not too hard for them to work the bugs out. Microkernel is very hard to do right (or all pc OSs would be microkernel by now), but it has its advantages. I'm not affiliated with the company, but I loved their OS, was very sorry to leave it.
Adam Smith, Midland ON