Interesting idea but I don't think that would be helpful for long. Anyone who understands pressurized air like a fire fighter, physican, or scuba diver please correct my very basic reasoning here, but I was looking at the Spare Air specs for their basic (yikes, $299!) model and it says it provides 57 "surface breaths" at 1.6L/breath, so that's about 90L of stored 02. If you're really huffing due to exertion or hyperventilating due to extreme stress, you could go through 90L of air in just 2-3 minutes by my reckoning and since there's no re-breathing mechanism, it's all gone at that point.

A few minutes doesn't seem worth it to pay $300 to escape a fire, even if you could make the assumption that you could reach safety in a few minutes from whatever situation you're typically in. A smoke hood that filters CO would provide protection against smoke for a lot longer, for much less money it seems.