Sorry but I'm not buying this whole 'learn to ride with your saddle up will improve your skills' malarkey. Frankly I think it's just plain wrong. I'm not saying don't do it, I'm just taking issue with what I believe to be a point of fact. Here's the argument.
To ride fast on any kind of trail other than up hill, the skills you need are basically about weight distribution. Nothing else on your bike, suspension, tyres, handlebars etc, makes anything like as big a difference to how fast you can go over any kind of terrain than where you place your weight on the bike.
If you've got your saddle up, then you weight will ALWAYS be in the WRONG place for maximising how fast you can go; you will always be limited to it being in more or less one place and in addition being too high on the bike, because you've got no where to go. Lowering your centre of gravity will make you more stable and therefore faster and that’s even before you start to learn how to balance the bike by moving around on it.
Sax keeps making reference to the saddle height issue being overkill for the UK. That comment implies (he might not mean this though so apologies if I’ve misinterpreted the comment) that the terrain isn't steep enough for long enough to warrant dropping your saddle but that's another big misconception.
People used to drop their saddles to get their weight backwards in order to ride steep terrain. But actually, being way over the back of the bike is technically the wrong place to be for most situations. The ideal place to be in balanced between front and back so you can balance traction between the wheels. With all your weight over the back, you've got no weight on the front and thus almost no grip for steering. On a DH bike, because of the length and layout of the bike, you don't need to be hanging off the back, although there will be exceptions. The reason we all do it on trail bikes is because trail bikes are compromised for riding down very steep terrain; it's not ideal, but its necessary to stop pitching over the front.
You can learn to ride fast on any bike with any kind of saddle height, but that’s not the same as being as fast as you could be or the same as developing the kind of skills that let you go even faster.