I fail to see how quickly shutting the hood in cases of catastrophic failure address my concerns. When you're dealing with pressure differentials and compressed gasses, explosions and implosions are a very real risk, and shutting the fume hood, even quickly, will not help in the fraction of a second these failures would take to fill your lab with aerosolized HF and shrapnel.

Even working at negative pressures, you can easily end up with a positive-pressure manifold if your sample is unexpectedly evolving gas at a higher than usual rate, or your valves aren't configured as intended. To be clear, these aren't academic exercises; I've actually seen all of these happen. With closed systems, you have to anticipate explosive pressures and plan accordingly. HF is incompatible with that kind of failure.