I am a mere amateur photographer and suspect I take far fewer photos than most here. I use both Capture One and PM+ and, for what it's worth, these are my views.
Capture One is an excellent RAW processor (I moved to it when Lightroom changed to subscription). The aspect I find trying is that all processing options are saved within the Capture One catalogue (although there is an option to create sidecar xmp files, of course).
I use PM+ (previously PM) to ingest and apply metadata to my files—because, in my view, there is nothing better. However, I find PM+ superb for cataloguing and finding my photos. It has infinitely better search and browse facilities than does Capture One and is very fast.
I appreciate this will not persuade anyone set on avoiding having two catalogues but, for me, it's just a matter of "horses for courses". Sometimes I just need to find something quickly and what would take an age in Capture One (if, indeed, it were possible at all) takes moments in PM+.
Stephen