Another potential option, as an alternative to CloudFuse for mounting Rackspace Cloud Files as a volume against which you run rsync, you could run Caimito as a Cloud-Files-to_WebDAV bridge.
Then, while you could conceivably try to employ the Fuse DAV2 filesystem plugin with rsync and a bunch of special command-line options to get files up to Cloud Files via the bridge, I instead recommend "sitecopy", which at its core isn't terribly dissimilar to Unison.
Sitecopy does a GREAT job of pushing files via WebDAV to its target (even if our target is a fronted emulation layer to Cloud Files). This is because "sitecopy" maintains a local database of remote-end file metadata that makes for speedy batch comparisons vs rsync.
Caimito was surprisingly stable and easy to install and configure despite its Java roots.
You might conclude that using "swift" (mentioned above) might be a more direct vector to the solution, but this solution gives you a few more places to probe, dissect, debug and control the data flow.