I haven't used the specific models from Zhiyun and Feiyutech you are referring to BUT
I bought the feiyutech a4000 for my NYC trip and never ended up using it because it can't hold a charge at all. I would charge it full the night before and take it out with me in the morning, the battery lasted no longer than 15mins.
I friend bought the Zhiyun one for smart phones and the same thing happened.
All were returned to AMAZON.
I didn't have any problems bringing mine as a carry-on to EWR and back.