Shooting while standing a sling is objectively worse than using the Olympic position, at least when you're not snap-shooting like in a hunting scenario. For hunting a sling is beneficial while standing because you may need to aim and shoot within seconds. The Olympic position may take slightly longer to get into, but it provides a more stable shooting platform than standing with a sling.
Slings work to stabilize a bent arm to act more rigidly, but the Olympic standing position uses a vertical forearm with a straight line of bone support from the balance point of the rifle down to the ground. It's more solid and stable than having your support arm unsupported, but stabilized with a sling. It's the same reason you put your elbow on your knee when sitting/kneeling rather than using a sling in the same fashion as a shot from the standing position.
You can further stabilize your shot with a sling in the sitting/kneeling position, but using the Olympic position for standing shots doesn't really leave much benefit when also using a sling just because of the arm position to get your forearm vertical and resting on top of your hip bone. Olympic position is far more stable than the traditional standing position with a sling, however.
The other thing is that I have literally only encountered 1 PRS event where you had to shoot standing unsupported. I haven't heard of any other matches that required that shooting position, meaning that standing unsupported (where the sling vs Olympic position debate is even relevant) is incredibly rare, at best, or more non-existent in PRS in 2021.
I imagine it works quite well on stable obstacles, I haven't tried it myself but I've seen others use it with great success. My main concern would be how usable it is when your obstacle isn't perfectly stable itself, I know I've been to a good number of matches where the PRS barricade itself, or a wall with shooting ports, had its own amount of wobble. Pulling against an obstacle that isn't perfectly steady seems like it might be counterproductive, but if your obstacle is sturdy then it seems great.