No significant improvement to Alan Shepard....
What about the fuel efficency alone.
How much fuel would the mother ship burn? Two small turojets at high altitude for an hour...maybe 1500 to 2000 kgs. How much fuel on the small rocket? It can't be much as the craft isn't that big. Gas and rubber. It really is Mach 3 sub-orbital on a shoe string.
When you work out the efficency compared with the Shepard flight it's amazing. And this is for a three seater (they filled the seats with weight to simulate paying passengers).