Should fatigue go down faster depending on how high up you are?

Meh... I think that's just adding a bit too much. My guy is a hero, no altitude will make me tired. Be hard to fight dragons up there if that were the case.

It would be an interesting feature as far as realism goes. Though I think it would be more suited to a hardcoe mode(if implemented), because unlike Oblivion it seems like fatigue is actually going to mean something this time around and it could get annoying fighting on mountaintops(which it seems we may doing alot of).

Interesting idea, however considering how many mountains there are, it would not work well in the game.

Dovakhiin, dragonbo... *gasp* hold up. *gasp*... dragonborn! *wheeze*

No. Dispite the fact that is 'realistic', it isn't 'TES', I don't want it in the game.

I'd much rather have extreme temperatures be an issue.

Well, just how high are these mountains going to be? Highly susceptible people generally experience altitude sickness at 7000 feet (or more, obviously), and I wouldn't call my future Nord 'highly susceptible'.