Josh,
As to you staement that the cost of E and C being the same, well I disagree:
E = clearance/traffic for IFR, any VFR info available, so clearance for say 100 movements per months ?.
C = clearance and separation for eveybody, so all of a sudden the +2,000 (guestimated figure) odd VFR movments plus the 100 IFR = 2,100 per month would require clearance and separation, a hugely larger number.
Whilst everyone is entitled to their opinion, and all opinions are welcome here, I think the majority of ATCs on this thread would disagree with you. I assume you are a pilot and might not be too familiar with ATC procedures ( behind the scenes).
Strangely, it can be much easier to control an aircraft than to provide traffic ... or ignore it. Let's look at the Broome example. All IFRs will be separated from each other ... whether E or C. The big difference is in how VFRs are treated.
In E, they will be unknown (to ATC). IFR pilots
may become aware of them ... either by sight or TCAS. The pilot, if in conflict, will want to take appropriate manouvers to miss the VFR. This will entail, if time permits, coordination with ATC ... and a subsequent "game change" all round. Big workload. If time doesn't permit, an immediate change of trajectory ... which again, will cause extra work "downstream".
In C, the Controller will have a prepared "game plan" and all aircraft will be processed within it. That is much easier than "cleaning up after the mess" .
So, what might sound like less work on the surface, may equate to more work/time/cost (for everyone) when you dig a bit deeper.