Unchecked As nothing ever goes to plan, there are scenarios where it is of tactical advantage, or necessity, to land on something other than your Carrier or LPH. I agree it may not be a high priority requirement, but it is a major advantage in high tempo environments where things have gone wrong.
EMC clearance is not a simple YES/NO. Almost all aircraft will have their limits, and operations will take them into account. Some limitations are more acceptable than others. Merlin Mk3 is based around similar equipment to Merlin Mk1. Therefore the EMC marinisation of Mk3 is likely to be simpler and less risky as there are more knowns than unknowns.
I'm not aware of what the Chinook has in terms of startup/shutdown limits in terms of wind strength and directions and how they compare with the Merlin.
Neartheend As for SK4 vs Merlin Mk3. How do the capabilities of the AFCS, Digi Maps, FLIR, Comms, etc. compare? Not disagreeing with you, sometimes simpler is better depends on your mission requirements.
Does the marinisation option of Mk3 include more equipment common to the Merlin Mk1 update?