Hi Doug,
As far as I am aware of,in your case, it is not required.
When you have ECC sitting on a different database and if your requirement is to bring data into HANA, you go for replication methods like SLT for real time replication or BODS for batch replication etc
But when you have S4HANA in place, your main database is HANA, so whatever data you bring into ECC would still be accessible or available in HANA. You wont need any replication method as such.
Regards,
Saritha K