Remember to backup your /dev/shm before reboot because it will be clean and you will have to resync from scratch again.
No need to resync but need a replay, if you have --data-dir set to a location on a disk. So actually for low mem nodes I'd recommend just let the shared file go if the disk is slow, as it's annoying to copy a 10G file from memory to disk before reboot, then copy it back afterwards.
I didn't pay attention to that flag. Thanks for correcting. Will add it now.