Yeah, except for the whole Dropbox making passwords optional thing. I asked AgileBits about this and they have stated that only syncing via Dropbox is supported at this time.
I very much want to find an alternate sync solution. I think it is kind of pointless to have a secure password solution if the underlying sync is insecure or more accurately has a dismal approach to security.
I don't know... why should I worry about Dropbox security in this context? The risk that someone could steal my Dropbox data is of course there, but that they then would be able to decrypt the password database (or bother to spend resources on trying) seems very unlikely.
The only thing I'm a bit worried about is accidentally deleting or corrupting the password file, as Dropbox could then synchronize this change across all devices. I guess I should back it up regularly to non-Dropbox folders to avoid losing all my passwords.
Dropbox would keep the old versions.
Unison works okay for me between laptop<->desktop. I don't think there are mobile clients, it is nowhere near as comfortable as dropbox, requires a crontab entry, and sometimes requires CLI intervention when there's a conflict.
But it's the best I have found to get folder-sync for sensitive stuff (my notes folder) without relying on a 3rd party for storage or security.
I've been using an svn for this purpose. I can sync my password dp (and config files, project files, etc.) between my computers and n900 pretty easily. It's not quite as easy as a dropbox-type of synchronizer but it has some added benefits too (history, pretty much all platforms support svn, so on).
The downside is that I sometimes have to enter the master password on my phone's on-screen keyboard, so it is probably shorter than it should be.