Just got back from the Dominican Republic. I brought the spark with me as a carry on. No issues with customs entering or leaving the country. No hassles flying jet blue either. I was nervous about bringing it but nobody even gave it a glance. But, in the DR and many 2nd/3rd world countries...
How much flight time are you getting from your spark? I am only getting about 10 minutes before I am forced to land. Three different batteries. And that is in wuss mode with no wind.