My point is simply this - saying "roughly 25% diminishing returns after reaching -450ac" is a bad way to describe what the formula does, because it is misleading.
If we didn't have the actual formula, most people would take that as "you get 75 AC for every 100 AC after -450". Which is not the case.
Again, thanks for the formula, Erelei. Please do not take this bickering as an excuse to say "this is not why I don't provide actual data of how things work", but more like, "this is why I should provide actaul data".
Math is a universal language that doesn't need translation.