GI/GF is good for low MP farming but they're also almost useless for high MP.
So I'm thinking, if the mobs can drop more health globe at high MP (not only when they die), the GI/GF build can be still very useful at high MP.
My proposal is to have mob a 10% chance to drop a health globe every (100/mpLvl)% health drop. it don't noticeable on low MP but at higher MP, the proc of the health globe drop can rise a lot and make GI/GF usable.
Stefan after giving it some thought I would handle GF and Gi similarly, they should work off of monster health whose intervals decrease as MP goes up.
So the way you set up GF:
Monsters have a chance to drop a health globe every (100/MPlvl)% drop in health
Currently health globes have a chance to drop when the monster is at 75% health, 50% and 25%. So this is same as as your formula at MP4. Every (100/4)% amount of drop in health there is a chance for a health globe to drop. Keep this for Mp4 and lower.
In MP5 (100/5) %, MP6 (100/6)%, and so on all the way to (100/10)% at Mp10.
Do this for GI too.
Monsters lower 1 CD every (100/MPlvl)% drop in health, for all MP lvls.
So at Mp 0 and Mp1, it is at 100% monster health. At Mp2 there (100/2) %, Mp 5 (100/5) %.
With that said, I agree the C4Dog guys. That build makes good use of GF, and that's fine. I wouldn't change GF if they can use it just fine. Instead, I would focus my attention on figuring out a good mechanism for GI.