Having done a little bit of this kind of thing with Coastwatch Dash 8s, I can tell you the job has very little to do with flying an aeroplane and a lot to do with managing a crew and aircraft in a rapidly changing environment. The fun part of Coastwatch was always getting the call (often from three different channels--satphone, INMARSAT, and HF--at the same time) asking if you could be at a certain position and recover to a certain place. How long can you hold for etc? It sounds simple, but by comparison flying from ILS to ILS around the capital cities of Australia is a piece of piss. I'm thinking that SAR will be like Coastwatch but without all the mundane searches in between.
The challenge is not the flying. It is operating below LSALT at night in IMC by coordinating with 4 - 5 crew and trying to keep a mental picture in your head of where the land is. It is trying to put the aeroplane in the best position so the guys down the back can get the information they need. In the case of SAR it's getting stores to people in need when the weather is ****. Boats don't generally get into serious trouble on a lovely day. You're effectively making up an instrument approach on the fly using some nicely conservative rules and SOPs. There's no ILS to take you down to the perfect drop spot. It's all done by crew coordination and honestly it's not for everyone. there are plenty of pilots around who have a hard time coming to grips with the fact that the person in charge of the mission is not the captain.
There is also not the same support from ops that you might be used to in a more mundane operation.
An aeroplane is an aeroplane, but the job itself can be challenging.
I didn't really want to get involved in this pissing match but the guys who think the presence or not of an autopilot or autothrottle makes a difference to how challenging the job is have literally no idea what they're talking about.