The big question is does it work with no issues. The answer is yes.
Dual antennas are installed on the Optima 9 for redundancy and piece of mind. All testing and consumer usage has been done with a single "BODA" antenna in aircraft up to 42% with zero issues.
Don't be confused by Spektrum that attaches a receiver to every antenna. Dual antennas give you two channels to use. I guess that's why the giant scale guys use up to 8 antennas so they have more channels?
The Hitec AFHSS uses 20 channels and hops continuously and one antenna works just fine! In fact, The $50 Optima 6 is perfectly suitable for any giant scale plane!
Julez- The marketing guys have to have something to do!