Tom,
While I agree that a 25% change is worth thinking about. sometimes that % needs to be taken into the context of the rating. If you have something that is rated at 1000 lbs, you start with 100 lbs of force, an additional 25% is in reality, nothing in the scheme of things. On the other hand, if you already have 900 lbs on the 1000 lbs capacity item, The additional 25% will overload it considerably.
Even with going from 100 to 200 lbs, in the scheme of the 1000 lbs capacity item. While additonal is 100%, its an additional 10% of the capacity of the item. A small % in the overall scheme of things. Obviously, I hope, going from 900 to 1800 on a 1000 lb rated item is potentially putting you into a very dangerous position of breaking something. DEPENDING upon how the actual rating was achieved. One NEEDS to think about that additional force/lbs.
Marty