We want to keep many copies of snapshots on disk so that we can debug the problem afterward. However, the snapshot can be large, so we added a feature that allow the server to dump/load snapshot in a compressed format (snappy or gzip). This also benefit db loading and snapshotting time as well.
This is also depends on client workload. In one of our deployment where clients don't compress its data, we found that snappy compression work best. The snapshot size is reduced from 381M to 65MB. Db loading/and snapshotting time is also reduced by 20%.