Finding what 'might be a target' is exactly what sentinel does? As is working with other assets for PID. It is effectively son of CASTOR after all.
Why waste many hours searching a large area with the high-res UAV camera when you can instead discount 98% of it with Sentinel and key the FMV onto the moving vehicles/static vehicles that have arrived since yesterday instead?
I'm not sure what you mean by preferring the Sea King model? Surely it's the same model as Sentinel but just no SAR? The SKASaCs mission kit is world class but it's unfortunately tied to a poor radar on the wrong platform. If the navy ever get the funding to fit the mission kit to Merlin with a modern radar then they will have a truly fantastic system.
Raytheon may have screwed to contractor support element but El Segundo managed to build a bloody good radar in the Sentinel DMRS. It easily outperforms ASARS-2 and JSTARS, so much so the US chose a slightly modified version for the P3 LSRS. It had its teething troubles but what platform doesn't? Why it seems to have acquired this name for itself within certain part of the int world as useless is beyond me? Like I said though, academic as there's no money. We can continue the debate at Cosford or Hendon (or more likely Bravebridge Scrappy).
Orca - you missed adding other top-level intelligence calls such as 'activty reduced during the hours of darkness'. My favorite in the CAOC was a SAR of Misratah (or some other port) with a huge ship-shaped return in the middle of the docks labelled 'UI Object Arrived at Port Since Previous Image. IA Comment: Possible Ship'. Balls on the line analysis reminiscent of Arnhem there!