Open Source DB search

We recently join a larger company that balked at the fact that our product uses MSSql and wanted us to use a database option that was either free, or didn't cost so much.

We use our databse not only for normal inserts/update/deletes/selects, but we also heavily use SQL replication to mobile computers (using web merge replication). This means that we use multi-master (sort of) asynchronous replication. I've been looking at several other options out there, and can't find anything that fits this bill. MySQL only allows master-slave replication, and the clients need to be able to update the database (often in a disconnected state), so this is out. PostGreSQL looks great, but slony doesn't suggest using itself for replication if you have more than a dozen databases being replicated (we plan on having around 200), and mammoth only supports master/slave. Bucardo looks like the only option that can handle asynchronous multi-master, but it only works on linux boxes, and while I'm okay with making our server a linux box, we are a .Net shop and all of our clients are windows users.

It's looking like we'll move to PostGreSQL on the server, keep SQL CE on the clients, and just create new web services to do all of our replication in house, instead of letting MSSql do it automatically for us. Basically we're talking a couple of months to make our program do again what it already does well.