So we got the Terrano units yesterday. Installing them inside the helmet, and pairing with the cell phones, were easy. Pairing the two units to work as intercoms was surprisingly challenging, and the fold-out paper quick guide was not much of a help. Finally found a YT video from the company that helped pair them. Went out riding with my wife, and struggled again to pair them, but after I finally succeeded, it was smooth sailing.

The units fit comfortably in the helmets, and the open ear design makes it safe by not blocking ambient sounds. The quality of the sound is exceptional, even in mild wind. We were both very pleased with the ability to communicate while riding and am very happy with the purchase; would buy again. Never listen to FM radio anywhere, so have not tested that function.