Note to Wayne:
Yes it [bleep]ing is! :lol: Well, in my neck of the woods anyway ;-)
Back o/t.
Those bikes tend to be massively overbuilt out of thick guage aluminium, with much of the framework consisting of forged sections for strength at the expense of weight. Too much flex in a frame makes accurate placement of one's front wheel difficult and the bike won't handle as responsively. Aluminium doesn't flex well and tends to break suddenly and without warning.
The secret is in the suspension and geometry. Freeride/downhill bikes push the riders weight back over the rear wheel while bringing the bars up high. When downhilling, you want to be as far back as possible so that you're not fired over the bars.