Evaluating Dropbox and Syncplicity: A First Comparison

Both Dropbox and Syncplicity are in beta stage, so I suspect this comparison to be "dated" early.

First, let's start with some commonalities:

• transparent monitoring for changes
• file revisions
• encrypted transfer
• web-based browse/restore
• easy online publishing/sharing

Both use Amazon Simple Storage Service (S3) as storage backend. That's fine with me, as Amazon is likely to have better reliability and scalability than any home-brewed server farm.

Dropbox has a very simple application with no windows or configuration settings whatsoever: The tray icon shows if it's currently syncing, you can open the dropbox folder from it, and open the web interface. For everything else, like a list of recently changed files, you have to check their website.
The current client uses about 1/3 of my upload bandwidth when syncronizing (~30kb/s). There is an early version of an updated client available on the forums with apparently improved background transfers, resulting in higher speeds.
Right now, Dropbox offers 2GB for free and unlimited file revisions. I'm not so sure how they want to keep this as a free offer once the beta phase is over, and they don't have any pricing information published yet.

In comparison to Dropbox, Syncplicity's client software is more comprehensive. Syncplicity also allows you to select arbitary folders to be synchronized. They have a pricing scheme online: Their free account has 2GB storage, allows to sync 2 machines and keeps five file revisions.
Syncplicity synchronizes files that are locked by other applications; I haven't tried this, and I cannot say how Dropbox handles locked files.

Restore:
In Syncplicity, if you delete files and want to restore them, you need to download them from within the web interface on a per-file basis. In contrast to that, Dropbox offers to restore files and folders to their original location within the dropbox - you cannot speficy a different location, or download deleted files individually (without restoring them to your original location) though!
Personal opinion: As a real backup solution, both services fail. I want to restore files and folders to any location, in any previous revision.

Synchronization Conflicts:
If I read correctly, Syncplicity "branches" on conflict, keeping both versions. Dropbox keeps only the first version that reaches the server, but copies the conflicted file with a suffix like "(conflicted copy 1-25-2008)". I haven't tested the conflict management, which would be a necessary step before using both solutions to collaborate.

I haven't tried publishing and sharing of files at all, so I cannot really comment on that. Dropbox seems to have photo gallery support built-in, so you can publish folders and people can conveniently browse your pictures. Syncplicity cannot publish folders (yet), only single files.

Security/Privacy:
Unfortunately, neither Dropbox nor Syncplicity allow users to specify encryption keys. Both state that the files are stored using AES-256 - I'm not so sure if that's true because you have direct clickable links inside the web interface (and can publish direct links), and even if it was true, it doesn't really add much security.
I know that with the sharing and publishing mechanisms, encryption is not easy. I'd want to see a way to encrypt selected folders with individual, asynchronous keys, that cannot be used directly to publish files.
I have performed a few short tests with a TrueCrypt container, with interesting results: The Syncplicity client seems to rely on file change dates - by default, TC doens't update the container date, so Syncplicity won't notice that the files changed. I'm not sure if this is good, as it might affect other files, too, and cannot be judged from the interface. For TrueCrypt, you can change the behaviour in its interface, but that doesn't help much: Syncplicity does not do incremental updates, so it'll upload the whole container every time something changes.
DropBox, in contrast, immediately picks up the change as soon as I dismount the container, even if TrueCrypt doesn't update the container date, and only synchronizes the changes. I've changed a few bytes in a text file, resulting in 8KB upload; a new file (4.1MB) resulted in 4.1MB upload.

Dropbox Advantages:

• unlimited file revisions (unsure if they keep this for free)
• incremental (delta) file upload
• has client software for Windows, Mac and Linux
• easy to restore deleted folders

Dropbox Disadvantages:

• only syncs one folder (but they're working on that)
• renamed files are treated like new files (new revision, old file deleted)

Summary:
Both services look promising and, at least with the Windows client, work as advertised. Nice work! A real comparison will be possible only after they both left beta phases. I'm curious about the Dropbox pricing scheme - both rely heavily on Amazon S3, so we'll see if they can differ much.

Personally, what I'd like to see is something I can deploy to my own server, maybe connected to my own Amazon S3 storage. I don't like having my files online at some third-party servers, without control over encryption and deletion. At least they should add the option to encrypt folders and/or files using local keys that are not transferred to the server.

Hints:
You can change the location of the Dropbox folder by modifying DropboxPath in HKEY_CURRENT_USER\Evenflow Software\Dropbox (stop Dropbox before doing that).

Also, you can add individual files from outside the Dropbox folder using hard links on Windows, and other folders by using soft links on Mac. Users in the forum report that Junctions on Windows do not work as Dropbox doesn't detect changes inside the junctioned folder.