I can see the arguments for and against here--and personally I would, and have been, more than happy to replenish the system in a Hangar---if you follow the basic and well established procedures the process is safe enough after all. My concern about removing a bottle is that you are opening up a system with all the inherent risks of ingress and contamination. Likewise, the removal --transfer to a bay--replenish-- test--certify--etc all adds to the overall cost for a simple replenishment in-situ. I can see the response about one fire etc. is more expensive---but I feel the O2 incident statistics would not support this. At least from what I can recall that is. Anybody know the last major oxygen incident that caused a hull loss ?.
Milt--you raised an interesting point about body oil etc---I am sure the RAF did an investigation along these lines a few years ago--but can't recall the findings. And on a personal level, I have always thought LOX was more hazardous than gaseous oxygen anyway.