re: Suborbital spaceflight - a dead end?
Well, the Russians had a man in orbit in 1961 without bothering with a suborbital flight beforehand.
In the late 50's, the US had the X15 and 2 Mercury flights in suborbital flights.
5 minutes of fantastic view could attract customers; 5 minutes of weightlessness could attract industries involved in microgravity processing (and find out whether it's worth it).
But that won't bring us closer to Mars, or even to the Moon.
Raoul