What were the estimates based on? Were they specific to your business, or just to your type of business? Can you refine them from the original/related resources at all?

There's a balance to be had between fuzziness in estimates, and specificity to your business, IMHO, and by looking to SaaS averages you're looking to reduce the fuzziness at a cost of specificity. That may well be a good idea, but it should be done knowingly, again IMHO.