FMRIPREP - SyN-based SDC versus fieldmaps?

Has anyone done a rigorous comparison of syn-based distortion correction versus fieldmaps in fmriprep?

I realized my fmap json files weren’t configured with an ‘IntendedFor’ flag AFTER running fmriprep on a dataset. At this stage, deciding whether to re-run everything with the fmaps configured properly, or to trust the syn-sdc results. All subject registrations are looking pretty good, but if others have noticed a clear difference in reg quality across the two methods I will consider re-preprocessing.

Any advice on how to proceed would be massively appreciated!