Agreed. I work on both vxWorks and Linux in the defense industry for a very popular armored fighting vehicle, and despite popular belief, the Linux kernel with the RT patch works well enough that both the cost of vxWorks and the issue of finding developers to maintain it isn't exactly justifiable anymore. Without going into too much detail, there have been a good few studies internally to show that our current fire control unit doesn't need the hard time precision it once required on legacy hardware, and all of the Linux ports with the RT patch perform just as well. The biggest hurdle, of course, is not exactly the performance. It's the certification process.