I founf my avid was the best brake I have ever used for down hill duties, it never faded at all and you should see how steep the hill are around here!!
Maybe it depends how you bed them in, I did mine by going to the longest steepest hill I could find and just riding down it, by the time I got to the bottom the brake was awesome. I do use a hope floating disk too, maybe that ressists heat more than normal rotors.
I had a mono trial, it seemed cool, but while at a comp on sunday I rode down a VERY small hill and all the power went! It would grap or lock, even with two fingers, all it did was make the worst noise in the world. I dont know it was because that pads glased or maybe it had a leak but I wasnt a happy chappy.