Immune to exhaustion/fatigue from movement?

[javcs]

Suppose that a character has an item that makes him immune to exhaustion and fatigue from movement. (It's an adaption from the Diablo II: Diablerie themed D&D supplement.)

Mechanically, what is the effect of this. Can the character just keep running/hustling over long distances indefinitely, or is it a totally useless ability?

 

[shilsen]

Yes, the character can keep running/hustling, but unless you find a way to eliminate the nonlethal damage from hustling too much, the character will knock himself out eventually.