So not to overtly threadjack, but I built https://secure.fracken.com/ as a lifeline for anyone who feels the need to jump ship from Flickr - sends everything to Dropbox, first 100 photos are free, everything else is a flat USD$1/batch.
While I appreciate what you've done here, it doesn't solve the real problem that I think that most people would have.
Downloading the files is easy. The real issue is putting them up somewhere else.
If your system moved them from Flickr to say, G+, then I'd pay you money. Otherwise, I don't see the purpose of this service as dropbox is more expensive than Flickr for storage and doesn't really have the same hosting options.
It exists solely for the transition - if Flickr's the only source for these photos, then (assuming you have a sufficiently hefty Dropbox account) this tool will at least get those files safely back in your hands. What you do with them afterwards is of course up to you, but this wasn't intended to solve a migration problem.
The photo-sharing site I made, OurDoings, will pull photos from a shared Dropbox folder and delete them after posting, allowing you not to be limited by your Dropbox quota. Hopefully someday lots of photo-sharing sites will have this option.
It's an MVP, but it works. Seemed apropos.