What are chances an external frame synchronizer tbc improves a signal with no dropped or inserted frames in vdub?
 

When capturing some tapes on different jvc decks with internal line tbc and dnr enabled I still see some anomolies and artifacts here and there.

All the captures thus far in virtualdub show no dropped or inserted frames. I remember reading that vdub may be lying about these statistics but assuming all was well would placing a quality external frame sync tbc in the video chain improve the video? I also remember reading that external frame sync tbc are said to be for improving the signal quality and not sos much the video quality. Is there anything I can check for to verify if there is room for improvement thru using an external frame sync tbc? Or do I need to just buy some units and compare results?