Row based replication on slave where as statement based on Master
You shouldn't have any trouble. For you replication you use the binlogs in the master, and the your slave reads them and "translates" them to his relay logs. Then your slave executes that relay log and for the replication, that's it.

In fact, you have already "different" settings, since you weren't doing any binlogs at all in your slave, so enabling RBR won't do any harm.