"Moe.exe" seems to be using a little more CPU than I'd expect (still context-switching away somewhere in the CLR), but overall it has much less system impact than I'd previously experienced. It seems to be keeping a lot of log files, and maybe (I'm hoping?) because this is a beta, some of them can be turned off in the future.
The only annoying thing is that Picasa keeps noticing changes in the Mesh folder. Files that were in sync days ago are showing up as changed, about once an hour. Odd.
Currently the major missing pieces for me are these:
1. Mesh is "PC and cloud" only. That seems to mean NTFS/HFS+, local filesystems only.
2. You can't sync to a network drive, and you can't install on Linux or Solaris. So this makes my investment in seriously awesome NAS kind of useless.
For installing on your server, the Linux/Solaris (inotify, FEM) equivalents to NTFS ReadDirectoryChanges are a little less mature, but it's certainly possible to code against them. (Wine supports inotify and dnotify for Picasa!) Crashplan supports Linux and Solaris, today.
PC against NAS sync is actually a harder problem. Even FindFirstChangeNotification/dnotify-level events over NAS turn out to be flaky in the implementation.
However, file locking does actually work (with at least 1-second-level precision), and it is possible on NAS to log all changes to particular files, and poll them from remote PCs.
So I really believe that a winning solution in this category will (a) support network filesystems (b) support UNIX/Linux hosts, and (c) use fewer resources on the desktop than Mesh does today.
But if you have a Desktop/Laptop combo, and you're not out of space yet, I can recommend Mesh for your basic sync p2p needs.
If you want a cloud backup or you're willing to pay for storage, and you don't mind the limitation of sync'ing from a particular folder, Dropbox is more efficient and tends to be faster to notice changes as well.