I haven't shot a PRS match in nearly 3 years due to work but I ran 243 in an AI or custom when I did and I really couldn't find any cons to it. I ran 105 hybrids though so I can't comment on how the 115's do.
Pros:
1. Lapua brass
2. Barrel life (with H1000). You need to run a 26" to really be efficient with this powder but a 22-24" will still net over 3k. I saw 3130-3145fps from about a half dozen different barrel from 3 different manufacturers all finished 26". All gave single digit ES and SD with 47.5gr and federal 210's in Lapua brass. Load development really wasn't even needed. With H1000 you'll see 3k rounds minimum burning down some ammo, 4k rounds if you do less missing. If you're going to run H4350 or another faster powder there's no advantage to 243 as far as barrel life and you won't see an advantage to the larger case capacity since you'll hit pressure at about the same velocity as you would with other options.
3. Brass life (with H1000). It's very low pressure and simply does not beat up brass. Lapua brass goes 10+ firings before the pockets even loosen up at all. 15-20 firings before it's loose enough to be a concern for me and I wouldn't want to depend on it for a match.
4. Brass loss at matches. Nobody shoots 243 so you're not sorting through creedmoor brass with 10 other people to find as many with your markings as possible after each stage and hoping someone doesn't accidentally grab your brass. Therefor you recover more.
5. Feeding. This is more so for non AI rifles since they just seem to feed everything so smoothly, but the shoulder angles feed a little better in some rifles (mainly R700 footprints) than some of the stuff with sharper and larger shoulders. Not that they don't feed reliably in a properly built rifle, the shoulder angle of the 308 family just feeds really smooth in everything. Not a huge plus but it is nice.
6. The ability to get and use factory Winchester brass which is also great quality and consistent in a pinch and for about 1/2 the price of Lapua.
7. Pierced primers (with H1000) are non existent and eliminates the need for a SFP rifle. Moot point if you're buying or already have a rifle with a SFP though. With the faster powders you can still pierce them if you don't have a SFP, it's just a pressure curve thing.
The majority of the advantage really comes down to running H1000. If you're not going to then there are fewer advantages which may or may not be worth it to you.