I don't know about starvation mode dangers, but I do know that it's been over 2 years and my health is better than it's ever been... no cholesterol issues, my A1C is almost to "not diabetic", and blood pressure has been slowly dropping. My doctor is ecstatic. And the first place I lost weight was the belly fat that's supposed to be so bad for you. After the first 6 months or so, I didn't do the extreme, extra-low keto because I just didn't feel comfortable with not having a wider array of vegetables (and their nutritive values) available. I still don't eat grains, sugar, honey, or milk except for cultured milk products (butter, cheeses, kefir, buttermilk, yogurt), and my total carb intake for the whole day tends to be less than what most people have in one meal.
I think that the reason there are so many different diets out there is because no one diet works for everyone; just like there are so many different pain killers available because not one of them is perfect for everyone (for instance, we discovered after surgery that morphine acted like a placebo for my mother but when they gave her hydrocodone it helped with the pain). You have to find the one that works for YOU.