I just picked up the GSI version of this cup but have a couple questions for those of you who currently use the cup based on your experience.

Do you simply stack the 2 when they're in your pack, or does the cup stay on the bottle when you are using the bottle (but not the cup)? If the latter, do they stay together naturally or do you find you need to use something to keep the 2 together?
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Victory awaits him who has everything in order — luck, people call it. Defeat is certain for him who has neglected to take the necessary precautions in time; this is called bad luck. Roald Amundsen