Ask HN: Quarantine (dangerous) Internet traffic with VirtualBox?

In order to improve security on a developer machine, how much sense does it make to "quarantine" (potentially hazardous) Internet traffic by using a virtual OS (such as with VirtualBox) for it?

In other words, here's the scenario:

- Host OS: used for "sensitive" data/applications (code, login credentials, etc.)

- Client OS (virtual): used for all Internet traffic activity (Web browsing, email client, SSH client, etc.)

And what is the safest way to manage the data-transfer interface between the 2 operating systems? Would you use shared folders? Or the shared clipboard feature? Or the drag-and-drop feature?