Martin, I stick by my conclusion, and here's why:
Your reference to 'an unpleasant experience' is right, but don't confuse 'unpleasant' with 'pain'. I don't claim the fish enjoy the experience. But on the one hand we have PeTA with a poster showing a dog with a hook in its mouth and, by implication, telling the world that fish feel the same pain as a dog.
I reckon we should start telling the world that such statements/implications are a load of rubbish, and we can go a long way towards doing that by relating incidents like the pike captures that started this thread.
I wouldn't argue with any of the points you make, but it still boils down to this very simple fact:
No creature that feels pain anything like we do, would never, in such a short space of time, repeatedly return for more of the same. A creature that feels a modicum of pain would still have been in too much pain from the first experience to have any desire to feed.
This is the message we need to get across to a general public where the majority soak up Sun-style news like a sponge. Unlike PeTA's message, ours is a truthful one and based on hard evidence, not supposition and bare-faced lies.
The FACT, according to everyday evidence seen by anglers, is that no matter what the motive is for a fish taking a bait, they would not be able to do so repeatedly in a short period if they felt pain.
And that's not scientific evidence, just plain old common sense that even a gullible, non-angling public, would understand.