I have only been exsausted 5 times since the system was put in and I run around as much as I walk, and my pc has a low strength score and im quite often reaching my weight limit when I pick up things. I think the exsaustion thing is greatly over exagurated by most people who talk about it. I cant really see why this feat would be much use, good idea though, I just think that with what system we have in place, it not going to make much of a differense.
One's experience of exhaustion varies by playstyle, character abilities and class. I know it affects me differently depending on what character I am playing. I will agree, however, that in its current form it is much more balanced than in its earliest versions.
As for the feat, if it bundled together several minor perks it could still be a decent feat (IE mild cold and heat resistance for weather situations, hunger and thirst resistance, and exhaustion resistance).
I will admit that only increasing a characters threshold for Exhaustion may not seem like much up front, but that could mean a lot more than most people think. From my understanding of the Exhaustion system, Your threshold is 10 + Constitution score. Once you hit/exceed that point, you become slightly exhausted, which, honestly, is hardly a problem except for lower levels and in dangerous dungeons.
From there, Your threshold * 1.5 is the point at which you become Exhausted (the one where you actually take movement penalties). This can be crippling to just about anyone in any situation, but often takes a fair amount of time to get to this point.
Even further, I believe at Threshold * 2-3 (still not positive) is when you become Extremely Exhausted, which is where you're pretty much reduced to walking speed.
So, for example, my rogue with his almighty 12 Constitution would have a Threshold of 22. His Exhausted threshold would be 33 and Extremely Exhausted threshold would be either 44 or 66.
Were he to take this feat, those three numbers would change as follows: Threshold of 26. Exhausted Threshold of 39. Extremely Exhausted Threshold of 52-78.
So, as you can see, that measly +4 may not seem like much, but it can quickly add up. Especially since the difference between him being Exhausted (second stage) would be another full minute or two of running and nearly 3 minutes of non-stop combat. Really, that's saying something for one lousy feat when you consider how long that really is ICly.
Though, I can see some minor bonuses to things like the Thirst system in Har'Akir and Weather systems as well, but again, I'm not sure if that's even possible. We'd have to have a Dev make a statement.
