Backing up on version 4.x and restoring on version 3.x


I have a cluster composed of several servers with a version 3.1.3 of couchbase, I have another set that I replicate all the data to (version 4.0.0).

My question is, can I backup (cbbackup) the data on the replicas (version 4.x) - and if, in a case of emergency restore that data on the rest of the cluster (version 3.x)?