That's always been the issue with harness bars, or using harnesses in general that don't have an inertia reel.
It's a risk you take, although I don't think it's a huge one. We've even seen pics on this site of gvr4's in nasty rollover accidents with the roof still totally intact. It's been a few years since the pics of that ricey pile of sh*t surfaced though. That said, I should probably go knock on some wood now. /ubbthreads/images/graemlins/uhh.gif