I ran some on my DH bike for 18 months or so. They were pretty good to be fair, but they weigh newly twice as much as the Formula’s on my little bike, and arn’t really any more powerfull.
I sold my bike and them, ended up with a cheaper bike and some XTs on it. Better modulation and a slightly lower power level, but a third of the price, so happy days.
Not sure why people are running them on anything other than a DH bike though, unless you are a serious brake dragger, they are overkill. Learn to ride off the brakes a bit more imo.