Let's share our pain...

Here is an interesting thought-experiment from A brood comb:

Two cyborgs, Michael and Ethan walk on the surface of a distant planet after a fight with alien troops. Michael notices that Ethan’s finger has a hole in it.
-Does it hurt much? - asks Michael.
Ethan unscrews his finger, and hands it to Michael, who replaces one of his own fingers with it.
-Gosh, that hurts a lot - says Michael.
-Thanks for sharing my pain. - says Ethan. -Now give it back to me.

Does that sound right? If so, why? If not, why not? Read the discussion here. Now, is it more plausible than something like the following?

Two cyborgs, Michael and Ethan walk on the surface of a distant planet after a fight with alien troops. Michael notices that Ethan is smiling.
What is it? - asks Michael.
I am feeling a tremendously pleasant sensation in my finger. - says Ethan.
How does it feel? - asks Michael. Ethan unscrews his finger, and hands it to Michael, who replaces one of his own fingers with it.-
Gosh, that really does feel pleasant - says Michael -Thanks for sharing your pleasure with me.
Now give me back my finger - says Ethan.

This seems a very odd story, and odder than the first. Why? Do we just not think there can be pleasure in Ethan's finger? Or if there can be pleasure there, is it less shareable that a pain?

UPDATE: The brood comb now has a useful reaction to this variant. Read it here.