The issue with IntegrityOS supporting C++14 is not the difference in feature set, but the time and cost required to certify their compiler and tool chain again. Unfortunately, certification methods don’t cope well with re-certifying modified software; you often have to treat it as a whole new system. If IntegrityOS has only recently got C++11 support certified then I don’t have much hope that C++14 will be coming very soon, but maybe they have a well-oiled certification programme and we’ll get lucky.