wow i almost forgot about the existence of sarong!!

u know what, i don't see the disadvantage at all - Just don't rock/swing too hard if you're worried.

sports or riding in a car would probably produce more impact than a nice rocking sarong...

plus yes, the motion helps with sleep, even as adults (u tend to fall asleep more easily in a moving vehicle)..

and; as for babies heads being rounder... could be true, i don't know