Larian Studios Forums Divinity - Original Sin Divinity - Original Sin - Enhanced Edition Sneak useless?

Level 20, armor rating: 299, reduction vs same level: 59%
Level 20, armor rating: 246, reduction vs same level: 31%
Level 20, armor rating: 206, reduction vs same level: 7%
Level 20, armor rating: 202, reduction vs same level: 4%
Level 20, armor rating: 198, reduction vs same level: 1%

Level 11, armor rating: 168, reduction vs same level: 38%
Level 11, armor rating: 140, reduction vs same level: 22%
Level 11, armor rating: 136, reduction vs same level: 20%
Level 11, armor rating: 119, reduction vs same level: 9%
Level 11, armor rating: 115, reduction vs same level: 6%
Level 11, armor rating: 108, reduction vs same level: 1%

Everything down to 1 armor rating stays at 1%, dropping to 0 only when you hit 0 rating. I may have exaggerated a little in my example, buy my point is that the majority of your armor rating is used simply to reach the level minimum where you get more than 1% reduction.