How scalable is SQL Server MDS? Has anyone worked with both MDS and MultiVue from VisionWare?

We have been responsible for implementing a number of instances of VisionWare MultiVue for several Local Authority clients.

We are now quoting for another Local Authority client and I would prefer to propose Microsoft MDS so that we can maintain a consistent tool set.

Is anyone aware of the differences between MultiVue and MDS? In particular, would MDS and its associated tools be as scalable as MultiVue? We would need control around 1000000 people with 100000 addresses.

Thanks very much for your help ...

Rob