This has been bothering me for a while now, but after seeing a few harpoon climbs which are 50% slowed, I think its time to suggest something:
The climb animation needs to be affected differently. Both increased and slowed climb speed just look really stupid. Like really really stupid. (No insult to the animators here, the normal climb speed animation looks great on all Monsters).
I admit, I am not really sure what would be the ideal situation, but what I would try for a week or a few would be to disable the scaling of the animation. This means that the climb always looks the same, but the speed still alters.
Another idea might be, to have 2 additional climb animations. The default animation would be applied within the range of for example 80% and 125% climb speed. Then there would be a new animation that was designed to fit 67% climb speed and would scale from there, and other one that would be designed to fit 150% and scale from there. For example.
Another, minor thing would be, that 50% slowed climbing would not result in 50% climb speed thus 200% climbing time, but rather a 50% longer climb duration. You know, instead of 100% * (1 - 0.5) use 100% / (1 + 0.5).
Just an idea.