Latest Info From Hitec Sales: Hitec will continue to provide Optima receivers for sale by Tower Hobbies, no explanation given why Optimas are still on back order by Tower. I'm glad a bought a 3-pack of Optima 6's before they ran out of stock at Tower Hobbies.
Aloft Hobbbies sells receivers that are compatible with Aurora 9 and 9X but they do not have the Optima's Supplemental Power Circuit (SPC) that provides read-out of motor battery voltage in flight on the transmitter touch screen.