I don't have one, but I remember when it first came out, I asked about the functionality of the O2 wrench on Benchmade's forum. One of the employees said he would get back to me. The next day he told me he had brought the knife down to the local fire station and tested it out, and the O2 wrench was definitely functional while the knife was closed. I think he said he ended up leaving the knife at the fire station, and a bunch of guys from there bought one for themselves.
I never ended up buying one because I moved on from my EMS job, but it certainly is a cool knife.