[Paolo Castellano]

Hello Adam,
VHS featured Composite recording on tape, so it is not required an S-Video connection. S-VHS tapes required (for better quality) S-VIDEO (video was recorded on tape as Luma and Chroma components).
According your equipment, recording to the BMD in S-Video could provide the same, better but even worse results.
BTW, if your VHS tapes are not perfectly clean, I think you will need a TBC (Time Base Corrector). I need it for my VHS captures. If you don’t have one, you could use a device that has one built in (like a DVD Recorder in E-E mode).

Best Regards,

Paolo Castellano
https://www.ivsEdits.com