Doug Messier has an analysis of the differences between Virgin Galactic and XCOR’s approach to commercial human spaceflight. A couple nits:

A year after the accident, Scaled brought in SpaceDev to assist with the engine development. The Powoy, Calif.-based company had built the propulsion system for SpaceShipOne, but Scaled subsequently decided to bring the engine development in-house. Bringing back SpaceDev was a tacit admission that this decision had not been a wise one.

It’s not quite that simple. There is some dispute as to who the actual engine provider for SS1 was, and SpaceDev certainly didn’t do it on its own. And one reason that they didn’t get the follow-on work was a rumored falling out between Burt Rutan and Jim Benson, founder and then-head of SpaceDev. In addition to the accident, I would assume that one of the reasons that SpaceDev and Scaled are working together again is a result of Jim’s departure from the company almost three years ago (subsequentprior to his recent death).

Also,

XCOR’s gradual approach – flying a small vehicle commercially, then building something larger – is what Scaled Composites might have done absent the involvement of Virgin Galactic. Branson’s company brought the customer experience to the forefront, which led to the development of a much larger – and more complicated – space plane.

It’s not at all clear what Scaled would have done (if anything) absent Virgin’s involvement. It’s unlikely they would have operated the vehicle on their own — that’s not the business they’re in, and they wouldn’t have developed it any further with their own money, because that’s not what they do. They build airplanes to other people’s specifications. Perhaps if Branson hadn’t stepped forward, Paul Allen might have started a passenger business, but we’ll never know now.