Huge contract? Not really. Especially when many larger clients whom you'd love to have for a reference will demand it. Take care of it up-front and don't wait until you get into contract negotiation. If the client knows you don't have a software escrow service already in place they may ask for the moon. Head that off at the pass and have it ready to go from day one.

In fact having it ready to go might help you clinch the deal. If you're part of an evaluation and you're ready to proceed and your competitor has to go and get this setup - you're more likely to get that business. Likewise if you're the competitor who's been caught with their pants down then you're more likely to lose that business. Every salesman I know is always looking for something to give them an edge for closing a deal!