Not much.
You will be SLIGHTY harder to reveal with detect hidden
Your deathstrikes will do an additional 1.91 damage
You will be able to wear heavier armor while stealthing. At 80 stealth you never fail a stealth check in all medable armor. If you want to stealth around in full plate you will need closer to 115 or 120 stealth. (Im not sure of the exact cutoffs for various types of armor. I always wear medable armor.)