I would say that a guy who does not finish in the top 30 percent in PRS, would likely be better off to compete with a 223, because a high performance cartridge is not going to make the difference for him.
From a technical perspective, larger calibers are inherently more consistent due to economies of scale.
For example a 0.2 grain powder variance with 50 grains of powder is half that volumetric percentage change of the same 0.2 grain powder variance with 25 grains of powder.
So its hard to get real low SDs with a 223 unless you are a heck of a good hand loader.
While this is true on a chalk board, in reality, especially in the context of PRS, it wont be the reason you missed the plate.
Advantages of the 223 is low recoil and better stamina over the entirety of the weekend.
If conditions are calm or at least steady, the 223 can chase a 308 very well particularly out to 800 yards.
If there is a disadvantage to the 223 it's spotting impacts. Several times at the end of a stage spotters have told me that I got more hits than they called. They added points back in at the end of the stage, but it still cost me points because I adjusted my point of aim after the un called hit.
Meaford last year used indicator lights though and that saved my bacon with the 223 and hits registered on the moose at 860 yards. So it still hits hard enough to ring the bell at that distance.
Anyone interested in going with a 223 for long range needs to make sure the rifle feeds from an AI mag and is chambered so the cartridge OAL is at least 2.500". If you cant feed the long rounds, then you will be much more limited.