A frequent question about replication is the overhead in the source, because in a lot of cases the source is production. Dbvisit replicate comes with the possibility to do the minimum on the source: only the FETCHER process is there to read de redo logs and sends it to the MINE process wich can be on another server.
But maybe even that - reading those critical online redo logs - is worrying you. That's not a reason to avoid to do a PoC with the production as source. Let's see how we can use the 'archived logs only'.