Fwiw, I recently did some experiments using the MIDI ports on my RME Hammerfall Multiface units - looking at audio recorded back from my Elektron units.

Timing via those is surprisingly impressive. I’m seeing negligible drift.

I’m not sure that a sync-gen type unit could improve on it much.

Those are connected via the PCI-E bus though. I’ve not had such good results with USB based MIDI devices.