I think this is very significant, and Rutan’s design is, to me, the most practical, versitile, simple, and effective of any of the X-Prize candidates. The simple truth is, this approach (air-platform-launched rocket plane) is tried-and-true, and could very well be the approach of choice for smaller countries wishing to get into space. It’s relatively cheap, practical, it can scale (imagine what a 747-sized White Knight could tote up there), and the rocket-plane itself can be made much more sophisticated if need be.
As noted above, the X-15 accomplished a lot, being essentially a very early prototype for the Space Shuttle. It scored the first hypersonic flights, the first breaches of space (67 miles), the first winged craft to go over Mach 6, first microgravity tests, and so on.
So what’s wrong with the fact Rutan emulated the X-15 to some extent? Besides, there’s still plenty of uniqueness. For one thing, no need for pressure suits; the cabin is pressurized. Its engine is relatively clean, cheap, and easy to build. It goes Mach 3! No private aircraft designer has ever gone that fast.
I see no reason why a bigger, faster, and more sophisticaed vsn. of Spaceship one couldn’t be built right now. What if it could make a sub-orbital flight across the US? Lots of people would pony up for that. And maybe a small piggyback rocket could launch things into orbit. I can’t see why not. A mostly-reusable space platform that could carry both commercial payloads as well as tourists at the same time could be a money-maker, I bet.
I think this is cool beans. If Scaled Composites can generate the venture capital and attract a bunch more crack engineers (and I bet the prestige of being the X-Prize winner would be quite a magnet), two things I don’t see as at all impossible, these guys could have an honest-to-goodness space enterprise in a decade or two. Yeah, they’re a long way from flying to the Moon or Mars, but so what? It’s still wonderful to see people accomplishing something like this without the shackles of Federal beaurocracy, and the more folks like this can accomplish, the better, IMO.