Hi Caerportis,
I first have to caveat my response with the fact that I have never tried to use Groove for this type of implementation so I can not comment on its ability to support this type of scenario.
I can comment about the Microsoft Sync Framework and its ability to support this type of scenario.
Firstly, you are correct that the Microsoft Sync Framework is a very scalable and easy to implement solution for offline data access.
Can you tell me a little more about where this financial data is coming from? For example is it coming from SQL Server or perhaps from other system such as an ERP system?
If it is coming from a relational database then I would suggest you might want to take a closer look at Sync Services for ADO.NET which is a component of the Microsoft Sync Framework targetted at offline and collaboration between relational databases.
I hope that helps,
Liam