I've assumeed a 5Dc is the original 5D, which is occassionally referred to as the 5D "classic" (hence 5Dc).
Re DOF, you can still get really nice DOF effects with a crop sensor with appropriate lenses. Ok, backgrounds might not be as blurred as medium format or even FF, but still quite nice. In addition, most recent crop sensor lenses are reasonably sharp wide open, whereas many FF lenses require stopping down a bit to reach a high level of sharpness. Reducing your aperture by one stop offsets much of the DOF benefits.
I've reassessed my whole FF vs crop sensor view in recent months. At lower ISOs, some of the better crop sensors are comparable with FF sensors. And with some high quality lenses being released by Sony, Zeiss, Fuji and others, the IQ differences between a FF camera and a crop sensored camera are rapidly diminishing. Unless very high ISOs are your thing, the only real benefit of a FF sensor is that it generally comes packaged in a much more capable, durable, faster camera body. You're essentially paying for the features, not necessarily significantly improved image quality over other brand's crop sensored cameras.