Yet when the chips are down and the development team has to set up a legacy system to replace the original helmet system, they go non-joint.
Here is a look at the Joint Helmet Mounted Cueing System. It is already in service with many of our existing fighter aircraft.
JHMCS is employed in the F/A-18C/D/E/F, F-15C/D/E, and F-16 Block 40/50 with a design that is 95% common to all platforms.This may also be integrated into the system of the F-22.
A more detailed look at JHMCS is here.
The F-35 program continues to absorb more of the DOD budget for no real worth.