You are correct.
Class C without RADAR is 100% safe as all traffic are known... therefore all traffic will receive either full separation, or detailed traffic. The only downside to Class C without RADAR is that the separation standards applied are Procedural not RADAR, meaning, more restrictions on IFR aircraft. This is the problem in WA outside of the coverage of the RADAR at Kalamunda.
Class E without RADAR is a large number of deaths waiting to happen... because no-one knows who's out there...
Class E without RADAR removes the ability of the controller to provide avoidance advice to IFR aircraft (especially fast, heavy jets carrying hundreds of passengers) when unidentified VFR aircraft are observed and a collision is possible.
Class E without RADAR and without mandatory radio monitoring and broadcasts from the unidentified aircraft removes the Call-&-Respond layer of safety... I can't see you, but I'm calling you and if you're out there, somewhere, please respond and we'll work something out.
Class E without RADAR, without mandatory radio monitoring and broadcasts, without mandatory carriage of Mode C transponders and even if they are carrying an operational transponder, choosing not to switch the thing on or failing to switch the thing on... is a call for carnage...
