I've been running FolderShare (a Windows Live Service) and Microsoft Groove (part of Microsoft Office 2007) concurrently for the last few weeks. Both products are Microsoft offerings, and both provide file synchronization features.
Which one do I like better?
FolderShare is lightweight and "just works". For over one year now I've been synching documents, IE favorites, OneNote notebooks, and scripts across 4 different machines with no issues. FolderShare creates a secure P2P network to perform the exchanges, and the only limitation I know of is the file size limitation (no files over 2GB).
All you'll see of FolderShare on your desktop is an icon in the taskbar notification area. All the sharing configuration takes place inside the web UI of FolderShare.com. Setup is simple, and there are no knobs to tweak and twiddle. The notification icon can give you some transfer statistics and tell you what is currently "in process".
Logging into FolderShare.com gives you the ability to download any file (not just the files in shared folders) from any of your computers that are online and running the FolderShare application. This feature has proven useful to me more than once, however, I'm sure some of you are having cardiac arrest at this moment by picturing your CFO downloading PPT files using a public computer with a keylogger installed.
FolderShare is smooth and simple.
Groove is geared towards enterprise level collaboration, and as such is a bit heavy handed. For personal synchronization of files, Groove is overkill. If you are working with a team and need to manage contacts, store and forward messages, configure alerts, and manage multiple identities - then the rich client interface of Groove will give you more features than FolderShare.
The downside is – sometimes I notice Groove is running (noticeable CPU and memory consumption during large synchs), and at least once I noticed Groove was not running – at least it wasn't synching files. Repeated tapping on the computer didn't fix this problem (it never fixes any software problems, but the physicality is therapeutic). Bits didn't start flowing until I restarted Groove.
Groove uses its own Simple Symmetrical Transmission Protocol (SSTP) for secure P2P exchanges, although it appears it can also deliver a payload over HTTP (using a corporate Groove Server).
FolderShare is all I need for personal use, but I wonder what will become of the product. There haven't been any noticeable changes to the software since Microsoft acquired the creators (ByteTaxi) in November 2005. The software is still listed as "beta" and the site contains copyright notices for ByteTaxi Inc. It would be wonderful if such a simple, easy technology was baked right into the OS.