Hmmm. Playing currently as a halfling ranger with Stealth proficiency. I am noticing some definite mechanical improvements for Stealth. I Stealthed the imps in the first fight. Stayed outside sight cone. Fired. Stealth check. Succeeded. Was able to fire again. Killed the first, but another Stealth check because the other two might spot me. Succeeded. Fired again. Stealth check. Failed. My MC was pulled into combat. Lae'zel wasn't in the fight. Sneaked her up to the edge of the sight cone. Fired. Stealth check. Failed. Pulled into the fight.
That's not a bad way of doing it. I mean, Lae'zel got her one surprise attack. My MC got surprise attacks until she was spotted -failed her Stealth check. By not sucking Lae'zel in right away, I was able to then navigate her into a decent position, which I wouldn't have been able to do if my MC had pulled them both into the fight as soon as the MC was spotted. So, in that regard, it's actually more realistic because I can't control both my MC and Lae'zel at the same time. It looks like they truly have done away with the sniping an enemy forever until they're dead. I mean, if you can keep stealthing it every time you fire, that's what Stealth skill is for. Enemies are just totally unable to find the sniper in the area. Granted, enemies should take cover as soon as the first is sniped, but cover doesn't exist in BG3 - which would make the game better, in my opinion, to have cover, but whatever.
I stealthed another fight too. As soon as the vision cone of one enemy hit my MC, I was spotted. So Stealth skill is for attacking outside of the cones. Also, I tried having Astarion rob Arron, the halfling merchant. Pickpocketing isn't as easy as it used to be. He failed every time.
So, the way I see it, the only real issue with the mechanics at present is that you can distract an enemy with one character and have a second sneak right up behind into melee range and knife the target in the back without a stealth check ever having to be made. Even if the person sneaking has heavy armor and has 0 Stealth, they can get up behind in melee range and hack the target in half with a greatsword. So, again, a single hearing ring would account for that, making it so that you have to make a Stealth check if you sneak up from behind and get within say Passive Perception in feet range. If Passive Perception is 13, you make a Stealth check when you get within 13 feet of the target. That's roughly 3-4 meters, I believe. If you're sneaking, you aren't moving fast, so that would prevent characters from getting into melee range before they are detected.
