Just figured it was interesting because there was an element of "when was the last time a ship fired on another ship anyway?" A Merlin operating at 15,000ft gives a radar horizon of ~280km, so depending on the radar and then tacked on to however far the helicopter operates from the ship and that gives a pretty good outer ring in the CBG.
I'm still quite confident about Vigilance, LockMart UK have been paid to run the competition for Crowsnest (including their own product) AND they are also the principle contractors for upgrading the avionics in the Merlin from HM1 to HM2 standard so presumably are more knowledgeable in the integration solutions possible for the aircraft.
It depends on how long they intend to use these things for, as Vigilance is the more costly option BUT it offers a more flexible system. Once Merlin reaches the end of it's life, I doubt we'll be packing away the radars too and i'd imagine any future solution would be easier to have external mounts for the pods rather than depending on some rear ramp solution or modifications to the cab to allow for a sliding bag arrangement.