The thing about not getting a good seal on the oxy mask is something I've found to be a myth.
It's just for appearances to the public.
Sounds like the sort of thing hard data is needed on. A casual look at the issue would indicate their has to be at least some reduction in performance, but is it significant?
This seems like an issue that a simple study with some people, decompression chamber and a variety of masks would solve.
And throw in a few smoke bombs into the mix as well.