Ceph at that time was unstable -- once I had a couple boxes kernel panic in testing, I jumped off that boat immediately.
Moosefs is pragmatic -- written in pretty tight C, performant, and the web UI for seeing the state of the cluster and how files are replicating is very nice. We have a small cluster with maybe a dozen nodes running for almost 2 years now with no hiccups...
"Important CephFS currently lacks a robust ‘fsck’ check and repair function. Please use caution when storing important data as the disaster recovery tools are still under development. For more information about using CephFS today, see CephFS for early adopters"
RedHat is focusing on making the block and object storage bulletproof. They're content to let the opensource side twiddle away on ceph FS.
Ceph was very interesting but wasn't product ready when I looked at it and since then it somehow never got to a stage where people would rave about it so that alone makes me think it's maybe too complicated. A bit like BTRFS which also for years and years is being developed and sounds really promising but never seems to be finally ready without gotchas.