Yes, it's dangerous. It certainly is play that falls under RACK. This means that it is important for you and the Domme to be aware of the risks and how to mitigate them. Are you healthy overall? Is the Domme trained in blood chokes? Are they trained in CPR just in case? These are reasonable questions to be asking.

I've have experience being KO'ed from Ju jitsu type chokes in sessions. It's always been fine (so far), but I'm sure to play with experienced people. I've actually dialed this back a bit in play, simply because I decided I didn't like being fully KO'ed. What's the fun of not being there? Instead, I do enjoy a choke that just get's me a bit woozy and more vulnerable. In the end I'm chasing an experience and IMHO a full KO is actually the absence of an experience.

But whatever you do, having the direct conversation with the Domme about risks and mitigation and feeling you are on the same page with them is important.

MMA players get KOed from chokeholds all the time. But of course, these are highly trained athletes. So results may vary. Be careful.