The problem I see with pushing lower class E is the increased workload for IFR getting clearance whilst trying to separate from VFR traffic in that narrow gap. Negotiating clearance and maintaining lookout and so on, you will start to need to get clearance prior to take-off and when not available because of multiple inbounds what then. Departing Armidale you will have 3000 ft to get clearance, or have issues like Coffs where you cant get airborne until all traffic in a certain direction is clear. And then trying to negotiate clearances while a flyaway of multiple VFR is converging on the same location and you need to manuvre to avoid RAs, but ATS won't give you clearance to manuvre because of multiple IFR in the area. Class E works well at altitude because the amount of VFR transits are low. I suppose within the class E at least they must have a transponder. This will affect RPT mostly that can not operate VFR so IFR pickup is not an option.