Regarding "cross border ops". We used to routinely do this. The only time a cost issue came into it was when a neighbouring force with no air support of their own asked for air support for a pre-planned operation, as they would for any other form of assistance from another force.
One point that seems to have been swept under the carpet so far. Helicopters sometimes get involved with long distance chases. Spreading resources more thinly (as per NPAS) will surely result in some vehicles / runners escaping simply because the helicopter needs to leave the pursuit to refuel.
It's actually very efficient for a helicopter reaching the edge of its normal operating area to pass on the job to the next ASU, who have arrived freshly refuelled and have the local knowledge required for many more difficult jobs.
In a national system the aircraft are likely to become stretched in terms of both fuel endurance and a lack of local knowledge of the crew.