The Elbit is clearly going to be cheaper in terms of a DOC.... it only has one engine. But one engine is deemed not to be enough when operating over people in a town or city.
What the Elbit (Watchkeeper) also does not have is 'sense and avoid'.... just how long have we been promised that and waited for it? BAE used to have the Jetstream they were trialling sense and avoid in.... when did they announce complete success? They did not.
It, an unmanned system with sense and avoid, will come in time but I bet your retirement will come a darn sight quicker.
Operating a light quad drone over a city is one thing but the Elbit is a big lump and no risk averse politician or Chief Constable is going to put a single engine flying brick over a city when the pilot has a field of view that is akin to a toilet tube. So what happens when the engine fails? Any volunteers to land a ton of metal in Hyde Park on a sunny day [and not kill someone] or better still try it at night guided by a GPS reference and that toilet tube view. Nightmare on.
In the meantime, perhaps, the Elbit will work fine over the North Sea [English Channel] , the Scottish Highlands and Dartmoor but unfortunately there is little or no crime there to make such a massive investment worthwhile. After all Police Scotland baulked at the idea of buying into a far cheaper and more flexible manned fixed wing to cover the northern areas just a handful of years ago.
The NPAS role is not to fly over water. Current activity flying drones and fixed wing (including Watchkeeper) in support of the MCA effort to halt migrant boat arrivals is a necessary step in the development of drones over cities but do not get to thinking this is going to happen before 2030. At the moment the powers that be cannot even get the Emergency Services Network (ESN) a 'simple' radio system to work on time let alone stuff that flies!