Firstly, apologies for the very late response. I see you've since had conversations with my colleague Ben, but for completeness, and for anybody else who comes across this, I have attempted to answer your questions below.
Regarding a way to achieve getting a database in sync with a new branch in source control: the easiest way is using our Schema Compare tool to compare from a check out of the files to the database server. Using this tool you can enforce the direction and thus achieve what you were hoping.
Regarding Get Latest: this feature was designed for users who decide to set up private (aka "sandboxed" or "dedicated") schemas for each member of the team, not for branch switching. So if Ben and I are both working on our our own private versions of a schema, both linked to the same repository, I can use Get Latest to retrieve changes made by Ben that are not in my schema. We use our schema comparison technology to make changes in a sensible, data preserving and dependency aware way.
I hope that helps. Ideally we'd like to introduce a much simpler "switch branch" feature in a later version, but it's not something we have immediate plans for.