One basic principle of diving is that the air supply at the surface is infinite and requires no equipment to utilize It is critical to be able to get back to the surface, or you die. The question under consideration is how you can get back to the surface in a variety of nasty situations. Almost all the scenarios under consideration appear to be thinking about the distressed diver as a universe of one -- I don't dive that way. I know I can take my 6' plus buddy, in double 130's, to the surface in a controlled fashion, because I have done it. I know he can do the same for me. If I'm twitching and thinking I'm going to tox, I'm going to be signaling frantically, letting my teammates know I'm not doing well, probably asking one of them for gas if I have any consciousness left, and they'll see I need assistance and escort me to the surface. On the surface, my fully inflated wing will float me; if I've simultaneous had an ox-tox event AND torn my wing in two, it may very well have been my Darwin day.
One of the things about internet discussions is that you can throw out scenarios until they get positively ridiculous, and show the weakness in any approach. But planning for three or four major failures gets absurd. For me to need to ditch weight, I have to have both my dry suit and my wing fail, and lose my buddy. That's a lot of failures in one dive, and I'm willing to chance it.