In my experience I have no problems ordering more than 120ml, but don't take a risk for more than 120ml, it worries you too much though..
I have made ordered twic from Nicoticket, recently order from Nicoticket, no broken bottle issues and happy with it.
I've ordered from killer juice twice, about 180ml on my first oreder and it got that through, but they messed up with my second order, i told them about it, but i am too lazy to send it back, so I choose to not order from them anymore.
Ordered from GV twice 120ml and 150ml and both orders contains leaked juice, they gave me discount codes and I'm satisfied with it, will be ordering more from them in the future since they also have Nicoticket on their line.
I Also ordered from smokelessimage.com but less than 120ml.
So in my opinion it depends on the vendor, if they do not have problems to alter your order on the customs document into flavoring rather than eliquid, i think you gonna be just fine.