Well, **** must happens sometimes. we had an LOA that was stating that this oxygen supplement was covering the use of supplemental oxygen requirement in the FAR, and leaving the 02 bootle intact for emergency use ( notwithstanding the confort of wearing the mask for 12 hours).
we have been ramp checked many times with this system, the FAA folks were actually looking at the pressure gauge of the bottle, but LOA rules and never had an issue with this system.
as far as decompression is concerned, this a whole different story i believe..