I find the new datastores interesting but I have my doubts. Has anyone ever worked on a long project (1 year or more) using an XML storage or an Object datasto

I find the new datastores interesting but I have my doubts. Has anyone ever worked on a long project (1 year or more) using an XML storage or an Object datastore. They can be a real nightmare. One reason: Users will always add new requirements: * We want another application, with different programmers, to access this data. When you have problems good luck defending your choice of datastore. And although the problems aren't related to that datastore, the programmers on the other team may place the blame on you. * We want to query tables that didn't have relationships in the beginning of this project, but do now * We want to generate reports: Max, Min, Count, etc.