Since the ROKs supplied the Tiger and White Horse Divisions in Chu Lai, I’m sure they damaged the efforts of the VC and NVA in quite a substantial way.
I am sure they did. I heard once that the reason N. Korea had been keen on sending their troops or military advisers to many third world conflict zone (in small numbers, though,) is that they feared their troops would lack real combat experience which SK troops were getting in Vietnam. On the order of tens of thousands of troops.