A good question!
Having flown both extensively in the mountains and also lots of SAR with the Wessex 5, the Wessex wins on power by a country mile. Effectively the same engines as the Seaking but far less weight. You could not see much out of the Wessex and the Seaking was like sitting in a conservatory by comparison but you sat very nearly over the winch in the Wessex so that positioning the hook with whatever was on it was very quick and simple. You could also pop the mainwheel of a Wessex on an outcrop and let people hop in and out! (Remember to have the brakes on!)
Once you come to finding where you were going to, the SK was in a different league. More radios than Currys and TANS et all. With the Wessex, lots of flailing maps and reading of road signs.
In turbulence the SK always felt as though it was going to come apart, (frame 290 probably!), but the Wessex always felt so tough and had an amazingly strong undercarriage for banging it onto the ground.
When watching the Coastguard S61s on the telly they often seem to be very short on power and are concerned to be in a position where an engine failure wont dump them in the oggin. With the Wessex some people did not even notice when one engined stopped!
At the end of the day I always felt that the Wessex was much more sturdy and FUN to fly but I suspect the SK has the edge technology wise to do a better job.
Now if you had asked about the Whirlwind 9
.
