C1 does not do integrated round trips to plugs like Aperture and LR does. I have yet to find any other DAM with a good round trip workflow to Nik, Topaz, DxO, Perfect Photo Suite, Pixelmator.....etc.
That isn't true anyone; Capture One Pro now supports external editing. How well it works, however, I dunno. I've only got the older version and haven't upgraded.