I just ran across this article by James Robertson of StepTwo Designs. The general point is that the best way to convey the requirements for a product is to create a narrative that describes the business need for the system. I like this strategy. It is a refreshing departure from the typical "column fodder" technique where customers create feature matrices to compare products. In addition to keeping focus on the business need, which is always a good thing, I think this technique breaks what I think are dysfunctional buying and selling habits created by checklist based selection.
On the buying side, putting a feature on a checklist makes an assumption that the feature (and the way it has been implemented) will solve a particular business problem. This assumption can be incorrect because there may be better ways to solve the problem. For example, auditing may be a more effective way of keeping a history of changes than versioning. Or, the feature may be implemented in such a way that it is unusable to the users.
I think that matrix buying leads to bad products as well. To compete, product companies need to be able to "check-off" certain features. This can either lead to marketing overstating functionality of the product or, worse, products growing un-useful features for checklist coverage. Having the most features does not make a product the best. Not only is there a tendency toward diminishing returns, there comes a point where additional features actually reduce the utility of the product by making it overly complicated.
So what do you do with narratives? State what your users need to do, and challenge your vendor to show how that goal would be satisfied with their product. If there is a disconnect (and there will be most of the time) have a dialog about how the product can be modified. Better yet, talk about how other customers have used the product to meet a similar need.
The narrative technique seems less quantitative than the matrix method. However, I think that these matrices are always less scientific than they seem. Focusing on narratives (both of the problem and the solution) is more work for both the buyer and the seller because they have to communicate a lot more. More importantly, the business users are more involved. They can visualize using the solution in their context. Just remember to control the natural desire for bright shiny objects.