They are not good power wise...
For trials, mtb, trail, normal cycling, DH, pretty much everything I've tried them on. I've had 3 sets, runned 2 of them on my trial bike. I've tried them on my mtb, and my dad who works with bikes who have also runned them on pretty much everything (not trials though) have the same opinion: They are not that good. They are light, and does look quite good, but the quality and the power is bad. They suck in the rain.
Oh, funny that you mentioned that!
The shop my dad works for sells complete bikes with formula brakes fitted. And so does the shop they cooperate with.
I haven't heard 1 person working with either selling these bikes, or repairing them, saying that they're good brakes. Everyone hates them, because that the fact that they are bad for everything, and have a bad quality. They have sooo many returns with leaking brakes, or just brake problems. And they have a lot of people that goes there and complains about the brakes, and buy new ones..
But meeeh, what do I know. I'm just a 15 year old Swedish tw*t..