I think the company focus is on system availability slightly more than disaster recovery basically to have zero downtime than have a few hours of recovery time. I've heard of instances where people use the Marathon array to be the master backup nodeof a Doubletake (a disaster recovery application) so that there is a assured running backup site for multiple locations. 55KM may not be extremely long, a long distance I suspect can be further extended since its just a dedicated fiber connection between. The real draw is theres zero downtime and zero data loss that I've not seen achievable in other DR solutions (they all has latency issues that result in some loss of data and downtime)