This isn't a Dropbox alternative by any means. From what I could understand, you need to keep two of your machines ON in order to sync. The best it could be called is replacement of your USB drive. AeroFS does something similar and it apparently doesn't require keeping two of your machines On at the same time, though it didn't work for me as advertised, so I gave up on AeroFS. Using Dropbox in the title with this, is…
I don't want a central service like Dropbox to host my files.
This design decision means that I must keep one or two of my machines on for my files to be available.