The KISS Principle

SpaceShipOne has a fixed nozzle so no actuators/hydraulics are required.

SpaceShipOne has no computers so there none to fail and no software to write/debug.

SS1 also has a great group of test pilots, something none of the other teams have. Of course SS1 is really flyable and it appears most of the other designs are "spam in the can."

They still have flight control surfaces, and the tail booms both fold in half.

It's true they don't need sophisticated flight control software. A regular tube rocket is aerodynamically unstable.

Then again the V-2 never had a computer, no pilot, and minimal control surfaces and that made 150 km with a one tonne payload. Then again it hit the ground at mach 3...

Also sophistication can make life simpler... I recon that SS1 likely has a fairly decent IHM system which will cut down on the amount of work nessecary between flights and the number of panels that have to be easily removable.

Mind you even if your test pilot blacks out/has a stroke/spontaneously combusts still glides pretty well all on it own...

This is described in detail in Milt Thompson's X-15 book, but the one time they lost an X-15 in flight a lot of it had to do with the pilot experiencing a vertigo episode. I wonder if the Rutan team has tested their pilots for susceptibility to vertigo?

Might I bring up again the fact that Burt Rutan has worked for many years on high-altitude research aircraft and was one of the biggest supporters for the Air Force spaceplane concept. Plus, he has four test pilots to choose from, undoubtedly at least two of which will be on the actual X Prize attempts. Even if one guy completely freaks, the other can still take over.

Vertigo is a condition related to the inner ear. It has nothing whatsoever to do with personality, courage, etc.

There are physical tests that can be performed which determine a pilot's susceptibility to vertigo.

Any mental anamoly can theoretically be overcome, regardless of its source. And I'm perfectly aware of the causes of vertigo; I was noting that even if one test pilot suffers from it, the chances that the other will as well are close to zero.