No matter what products you will use (SAP or non-SAP).
A triggers replication is based on the creation of triggers in the data source tables so that when this table receives a change to trigger is triggered and send the same change to the destination, thus compromising much performance from your bank.
A ETL (Extraction Transformation Layer) is based on a third room (could be used as an ETL product SAP Data Services) that connects to the database data source data, takes readings, processes this data if necessary (within the application layer of DS server) and performs other operations after the target database (insert, update, delete ...).
Best regards,
Angelo