The hip belt isn't going to let you carry a 30kg load, but then it doesn't need to. It's enough to take the weight off your shoulders if you overload it and other than that it keeps the pack stable and planted. I have never bothered to remove the padding because it just doesn't add that much weight to the pack.

The shoulder straps, though, THAT is the reason I love my beat up old Black Diamond Speed 30, and that's why nothing else I've tried has supplanted its place as my go to pack. Black Diamond developed a shoulder strap system called SwingArm which connects the base of the two shoulder straps by a small cable that runs through the bottom of the pack.

Without losing any of your normal adjustability, this system lets one shoulder strap get longer while the other gets shorter. This is the single best shoulder strap design I've ever seen on a climbing pack. Normally, when you reach above your head with one arm, the corresponding shoulder rises which means that you end up lifting a bunch of the pack weight with that shoulder. While you may not notice that sitting in your living room, it can accelerate fatigue on a long multi-pitch climb and beyond fatigue, it also potentially causes the pack to slip off the opposite shoulder - so without it, I have to use the sternum strap to keep the pack planted. SwingArm lets the shoulder strap get a little longer to avoid this, while shortening the opposite shoulder strap to transfer load to the opposite shoulder and keep the pack stable.