Not yet doing deco, but ...
... their back options options for a failed or lost decompression gas lie somewhere between going back to their travel gas (if carried), using their bottom gas (if not hyperoxic) ...
- What is the real world intersection of hyperoxic mixes for bottom gas in planned-deco scenarios? [yes, I can certainly see EANx for LONG shallow deco dives, but is that really a subset worth mentioning?]
- But, regardless, isn't a hyperoxic mix exactly what you want in a deco mix?