The trouble with Skylon is that all of these things you mention make it more <i>ambitious</i>, but they don&#x27;t really make it more <i>useful</i>.<p>The main advantage Skylon would have over the Falcon 9 is the fact that the Falcon 9 is not fully reusable because they don&#x27;t and can&#x27;t recover the second stage, while the entire Skylon is recovered.<p>That&#x27;s significant, of course. The second stage makes up about 25% the cost of the rocket, so that places a ceiling of about 75% on how much Falcon 9 reusability can save..<p>But then, starting from where the Falcon 9 is now, building a new rocket that can also recover the second stage doesn&#x27;t seem <i>too</i> difficult. It&#x27;s a big challenge, to be sure, but relative to Skylon it&#x27;s not too bad.<p>Skylon is certainly much more ambitious in terms of how it works, but it doesn&#x27;t seem to be very ambitious in terms of what it can do, which is not a promising combination.