Today I maidened my 3DR hexa-B with sonar. In my basement. It was snowing outside. Like crazy. Took it up about 2 feet. Moved it around a bit Set it down. And gasped for joy. Nice stuff. It has APM 2.5, v2.81 SW, ublox GPS, and sonar. Roll was fine but pitch was a bit twitchy - will be tuning before anymore flying.