[whpalmer4]

In short, you don't. It puts it in ~/Library/Application Support/OmniFocus/OmniFocus.ofocus and no longer allows you to specify another location. You could do the sync to disk option and specify another location (your Dropbox folder, for example), but your primary database will still be in the Library tree. I'd be a little cautious about trusting Dropbox with your data, as it doesn't understand the locking protocols used by OmniFocus to keep your data safe when multiple parties might be writing at once. I would personally just use a USB drive and the sync to disk option (or the WebDAV option if I had a suitable server available), unless some extensive testing shows that there is no possibility of data corruption.