There are a lot of elements not covered actually.
For example, the effect of objects on LoV (detection range) which also seems to be different to LoF (line of fire), i.e. some objects block the LoV but not the LoF.
Or the ability to leave combat, which also appears to behave differently. For example, it seems as if characters are more “alert” in combat, i.e. objects do not block their LoV, instead they do follow around corners and such, even if they currently can't see the player. Also when firing at a NPC while undetected, that NPC seems to detect the player and returns fire or approaches towards the player's position, while other NPCs only run towards the attacked NPC it seems.
It's a bit of a pity really. Sneak has a lot of potential, especially as a combat skill, but the mechanic is so weird, it seems impossible to use reliably.
Starting with the game failing to communicate that there are two sneak modes. A “normal” one and a “successful” one. It's just silly to toggle sneak on/off to check if leaving combat suddenly becomes possible. Or being detected seemingly at random when the game re-rolls sneak, and adjusts the Sneak mode without telling.
Not telling the player the numbers is a theme in Fallout, but game-play wise it makes using mechanics like this rather difficult and obscure.
Anyway, (after a lot of try and error) I managed to reach Rodriguez undetected (requires 100% Sneak and a Stealth Boy, plus I may have got lucky to get past the first Mexican guard on the 2nd floor, i.e. his LoV may have been blocked by a companion. At least, it worked or failed very irregularly, but perhaps my “sneak mode” changed either by reloading or the automatic re-roll, who knows). Either way, there is nothing to do up there, lol. Well, except perhaps looting the place without killing them all.
And I tried a bit of combat. At the camp of Super Mutants it is possible to do some damage by sneaking, firing and then stepping behind the stack of tires (who do block LoF, in opposite to barrels, btw
) to prevent the counter-fire. Then end combat, rinse and repeat. However, I'm not comfortable with that mechanic, i.e. I don't know what to expect most of the times, starting with figuring out behind which objects I can take cover, or knowing exactly when I can or can't leave combat. Besides it needs an attack that can “knock out” the target or some other means to avoid the alerted NPC, but even then it feels like a strategy that can very quickly go sour.
I think there is a lot of room to develop strategies but it's a bit awkward to handle, and it needs a lot of experimenting to figure out how it works, and even then it's still mostly try and error, as the game communicates very little.
For example, during combat it seems as if only the NPC shot at detects me (runs either towards me or returns fire), while any other NPC only runs towards the attack (aka the NPC shot at). However, another time (with MacGyver) it was impossible to leave combat. No matter the distance or sneak skill, MacGyver (once hostile) would always detect me and restart combat. Another time (first ghoul encounter) they were programmed to run towards me once I left combat (which was cool actually, didn't expect the mod to react to that). And last there is the general clunkiness of the mechanic itself, on top of its lack of transparency. So it's really hard to predict how the game will behave or react, making sneak a rather odd instrument. In fact, I'm still not sure what to expect when using it in combat, or how much is possible. For example, in regard to companions, or a melee “hit & disappear” strategy ala Riddick (with high sequence and a lot of AP (Bonus Move)) etc. Lot of potential, but hard to tap into.