<p><pre><code>   &gt; how much payload is sacrificed by the need to keep fuel
   &gt; in reserve for the return to base?
</code></pre>
Simple answer: None.<p>A more detailed answer is that building a system which can be reused is an economic proposition. So that the Falcon 9 can lift X Metric tons to orbit for $Y. The way in which they keep the value $Y low is by re-using the first stage. Every satellite project knows the throw weight of all the common launch vehicles and their cost per kilo. And that is how you plan you satellite design.<p>Now at the moment SpaceX gets 9 merlin engines and the first stage booster back for &quot;free&quot; (which is to say that the cost paid assumed it would be consumed in the launch) but as they learn what they can do they will use that cost savings to offer cheaper launch services (more business) until they have a full launch schedule and then keep any excess value for re-investment.<p>But an interesting question is this, given that they have a &quot;used&quot; first stage, who would be willing to launch on it? It has no track record and no reliability statistics other than it worked at least once before. To develop that information you need to re-launch them. And I&#x27;m hoping that SpaceX will make available some higher risk but lower cost &quot;seats&quot; on those test flights.