I'm still not a believer, particularly for runners and other endurance athletes.
A carb/glycogen diet is better at on-demand muscle energy and hydration, there's just no way around that.
Glycogen is stored IN MUSCLE FIBERS.
Every person I have ever known on keto diets has ballooned back up after introducing carbs back into their system.
I find it hard to believe that starving your body of glycogen OR fat is a good idea. Your body needs to be good at converting both.
That being said there have been a bunch of studies that show cancer feeds on sugars and glycogen, so if my genetic makeup pointed to a likelihood of cancer, I'd think about a high-fat diet.