I landed in DC and reassembled the Onewheel in few minutes.
It is such a fun productive and social tool to travel with - It opens a city like nothing !
Few hours before boarding (Paris -> DC with a stop in Reykjavik) Icelandair emailed me that the OW will be accepted without its battery, but the battery will be refused.
I then had a nice conversation with Future Motion support, they proposed me to send it for a repair in case my battery was confiscated (and charge me for tuning + missing part).
So i took my chance and put the battery pack (not the battery module, too big and dirty) in a plastic bag as a carry on. It is a huge battery pack, I wasnt sure what to say if i was asked. But it was scanned without any question.
Now I cross my finger it wont be confiscated on my way back !
ps: to remove and extract the battery, you actually ends up only a few screws away from unmounting everyting. unmounting everything makes it easier to pack, and probably raises less security and custom questions. but i agree it is not a necessity.