Another +1 for Hazel, it's indispensable. Another automation tool you may want to take a look at is Keyboard Maestro, I believe it has macros specifically for Windows Switchers too (including cut functionality). Oh, and Launchbar. One of the workflows you could take a look at is keep the file in your documents folder and create a symlink (symbolic link) to the file. It's like a shortcut, but at a lower level in the OS, so Drobbox reads it as the actual file. This way you don't have file duplication, but have access to the file in both Dropbox and your Documents folder. I haven't tried that for PB attachments, but it may work there also.
You can either create a symlink by using terminal, or by using a 3rd Party software that makes it easier (I generally use Launchbar to do it, but also use Forklift sometimes).
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