We use vReplicator where I am, although I'm not sure on license costs, it's based per machine though. The machines are snap shotted and copied every 2 hours from one host to another, SAN storage. This is done on the fly to production machines with no downtime. Can be scheduled for replication to any timescale.
It works very well and has pulled me out of a a tight pickle before. Having said that, if you can take them offline Veem FastSCP is very good. It is also a useful tool for managing different storage systems.
Edit:- Benefits are it's all automated and will email you if it gets a problem. No buggering about offlining machines, copying and so on.