Threshold vs Attrition Systems

Hit Points vs Hit Threshold; Fatigue Points vs Fatigue Threshold

There is a BIG system difference between the two, but they are easily overlooked.
I prefer to use Hit Threshold or Fatigue Threshold vs the latter. Why:

• I can dish out Tokens as Damage or Fatigue. Dishing out Tokens is Funner for me. 
• Special Tokens like special damage can't be removed unless a special action is taken. In GURPS Sleep Loss, Starvation, etc Fatigue is easier to track. "aggravated" wounds cant be removed as easily, so you can track the "Troll's" fire damage with a seperate Token and regular damage with another. 
• The math and conceptually is MUCH easier. In the Point system you "take" Damage and "subtract" HP. Is dmg a Negative HP value, did I just deal -5HP to Opponent Y? Then we go to healing - You heal 5 damage? Do you recover 5 lost HP or did you remove 5 damage? Conceptually

Its like Comparing Roll vs Target Number vs Roll-Below Score. You can have very similar statistics and probabilities  the advantage of one vs the other. In Target No. systems you have two places to Add or Subtract the Roll or the TN. In Roll-Below, you have only one value, the Score, which after all the modifiers have been applied Viola simple.

I remember back in HS erasing and recalculating damage, I gave myself a hard time.
The GM says you took X damage, you don't erase your HP and recalculate it, you keep that HP and start jotting down your damage.

Taking this to Your GURPS

Fatigue

...has all sorts of complications, because you can't recover Fatigue lost in a certain way normally. 

There is Fatigue Lost to Starvation, Thirst, Sleep*, and Spells., which can be recovered by 2 hours of sleep. You can't recover 

* If your a simulations like me, the "Sleep" Fatigue Token is gained every 4 hours in the day since you woke up. In the course of the day, you have Fatigue you need to sleep-off, that resting won't remove. 

Hits

Hit Thresholds Sounds better IMO. anyway, there is damage that can't be healed normally and there are different kinds of damage with special effects. Its easier to track them all with "Status Effect" props like Chips tokens or cards. The threshold system is much easier to use, and with a pencil you can create groups of damage: Special Normal etc.... You can have a box for "Leathal" damage, a box for "Stun Damage", where you scratch at it until it hits a certain threshold.  

Taking it to my Home Brew DnD

I'm using lower levels of Hits and Fatigue Thresholds in my DnD Game. (BLASPHEMY!!!) I've done some simulations "Playing with myself" in running scenarios to see how things turn out, it is lethal but Role-Playing Point Tokens negate that and require Players to take more initiative and narrate more.

Hits T. = ST x Carrying Capacity Modifier (like the bonuses from size: Large x2, etc).
Fatigue T. = Hit-Points as derived through Hit-Dice. Spellcasters can take as many Spell Fatigue Tokens equal to their Spell (Point) Threshold. Going Over Threshold converts the Spell Fatigue to Damage Tokens. So a Wizard Warrior can push Farther than a pure Wizard at the expense of higher magix, but a pure wizard can have so much magic it can consume him.