The remark about being able to close the valve quicker in the event of a fire only makes sense if it is an external fire in the close vicinity of the cylinder. Oxygen flash is not a slow process, it is rather fast, so by the time you reached for the valve in the case of an internal flash, it has already done its thing (how fast you can close the valve is fairly moot at that point, at least to me-I'd rather make use of that time to run.)

The remark about fully opening the valve causing deformation of the seat does makes some sense if you are in the habit of torquing the valve in the open position (sadly, I have met several who do this.) I try to approach full open, stopping just short of resistance to turning (open enough valves and you can almost sense it, open them slowly as you should and you can feel when you are there.)

Thanks for posting those links, there is some pretty good info on those pages