Again, the risks you mention are certainly real. However, I believe they can be almost entirely mitigated by always having someone present who's ready to catch or assist the sub if they start to fall, or to release them immediately if needed. That's pretty standard stuff in BDSM. Clear communication and closely monitoring the sub are the key. Also, it's very unlikely that someone would suddenly collapse or lose consciousness just like that without any prior warning. I'm not saying it could never happen, but the risk is quite low.

If proper safety precautions aren't followed, then yes, there's a risk of serious injury when using devices like this. But that's also true for many other higher risk scenes. I just don't see OBPs as riskier than things like suspension bondage or CBT/ballbusting, for example. In my opinion, the risks involved are different, but not greater or lesser. We can agree to disagree on that.