The puffers have been removed from the active inventory, with no plans to purchase more of them (not saying they WON'T make a comeback, but it would be about as likely as Ali getting in the ring one more time - what is more likely is a new tech that is more sturdy and checkpoint friendly will be developed and marketed at some point in the future). This makes the puffers a non-start issue, they are simply not a viable option right now. So the only viable (currently) way to check all passengers and bags for explosives would be ETD.