In reply to SidH:
I'm going to go with Dave on this one, I reckon the concept makes a lot more sense than layering, and the way I did it was fairly cheap as well.
I have never had a breathable enough waterproof that I can walk uphill in it with a sack on without ending up dripping in my own sweat. If one exists, I will be happy to try it out, but to be honest i doubt one does, and if it did it would cost a bomb. And that's in the dry - breathability decreases in the rain, so I would personally doubt that I could find a waterproof which would keep me dry walking with a pack in a storm.
So I gave up on it. I bought a pertex windproof, which allows me to walk in the dry without any breathability problems at all. And if it rains, as long as I'm still moving, my body will be generating plenty of heat, which is enough to drive out the water which seeps through the pertex back out again - I've tried this a number of times in manky weather, and it works well enough, I've not been cold yet. If it stops, I have a non-breathable sheet of plastic waterproof which cost me nothing which I put on. This I'll also wear if I'm retreating in the rain, abbing etc, since I'm not generating a lot of heat then either. Its the uber-cheap version of a micropile top thing.............. 15 pound for a cheap microfleece, 20-odd for the windproof, waterproof was free (but for something of similar quality, expect to pay at least £0.15 from a market stall (-: )
OK, so its not perfect, if the rain is heavy and I'm not moving I will get wet, although not cold, and if I put the waterproof on over damp clothes, theyll stay wet for longer because it doesn't breathe too well, I may get a cheap (£40 or so) lightweight (it doesn't need to be tough, it will spend 99% of its life in the bottom of my rucksack) breathable waterproof if I see one in a sale. And currently I've put too many holes in the windproof, but this will cost me a lot less to replace than a waterproof, and has stood up to as much abuse as I would have expected a waterproof to.
Think about it some more, see if you think differently,
AJM