What I've done in the short term is to use FlickrTouchr (https://github.com/tominsam/flickrtouchr) to retrieve my ~7 GB of photos from Flickr and upload them to Dropbox. The Dropbox gallery feature works quite well and has the advantage that you can easily backup/modify the underlying files.
In the long term I'd like to move the pictures to my own server (allowing me to use my own domain, etc.) and hack together a simple frontend similar to Dropbox' gallery.
If you decide to move away from a Flickr pro account (and if you also have non-public photos on your account) don't forget that after your account is switched back to a normal account you can only access the 200 most recent photos. So if you want to delete your photos from Flickr it's best to do so before the pro account expires.