well i would go for the backpack:
-cheaper than large pelican case ( not always, though )
-easy to grab
-easy to carry

to add the waterproofness / ability to folat of a pelicancase, just use a heavy duty waterproofliner. ( a thick survivalbag can be used like this too and has more uses ) Protectiveness to your more fragiale gear, can be done by rolling in to, clothing, blanket, sleepingbag, etc. If it need more protection, than put it in to a small container , before you roll it in to something.
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