Daniel,
I can marvel at NASA going to the moon all I want; but COST is the reason that Apollo 18 never left the dirt. 500% more efficient in cruise is only good as long as it costs less to actually design, build, certify, and be competitive in the real world aviation market. Technology has advanced dramatically since 1969, but the public is still not flying to the moon.
Honestly, GA manufacturing could be better served by mundane things like tort reform and easier to obtain STC’s.