We’ve got 11 speed on our Calfee. We’re a bigger (340 pounds) relatively strong (Cat 3 racing category) team and have had no trouble with the chain. Mileage appears to be about the same as10 speed.
As for packing the bike, our tandem doesn’t have couplers, but on my single bike with S&S, and packing our tandem in its case, I just take the rear derailleur off from the hanger, I don’t remove the chain, just pad the chain stays to avoid rubbing. Haven’t had any problems.
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You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.