Personally, at this point, I'm only interested in using the ingest feature to rename my files. Capture One's ability to rename files when importing isn't complete. The original number in the filename is not accessible as a variable in C1 for some reason, but it is in Photo Mechanic it is. And oddly in C1 there seems to be a bug when importing a folder with XMPs - it thinks the filename is taken in some cases and adds a "1" to the end.
So, my preference would be to have a switch that ensures the ingest absolutely never creates XMPs, or at least it doesn't if I'm not applying any metadata upon import.
I would think it reasonable if PM created XMPs as needed later if operations demanded it.