Also, I wouldn't be so quick to write them off -- their solution is based on Container Attached Storage (CAS), and is the only relatively mature solution so far I've seen (I haven't seen any others that do CAS) that sort of take the Ceph model and turn it inside out -- pods talk to volumes over iSCSI via "controller" pods, and writes are replicated amongst these controller pods (controller pods have anti-affinity to ensure they end up on separate machines).
I have yet to do any performance testing on ceph vs openebs but I can tell you it was easier to wrap my head around than Ceph (though of course ceph is a pretty robust system), and way easier to debug/trace through the system.