Concerning upgrading / flashing:
The WigWag Sensor and Relay are both upgradeable over USB, the Sensor, Presence Tag, Glowline and other products will also be upgradable over the air (OTA).
Developers must use USB not OTA. If you mess up a flash with OTA you are likely going to be pulling plastic apart and soldering.. but with USB you just reflash.
WigWag Dev Kits - Arduino and the 6Bee are all USB and OTA capable.