I pondered this situation a few years back, having a number of .223's, 20P's and a .17 hornet on the small end- and 6BR, 6 Dasher and .243 on the "upper end" for varmints. I wanted to shoot a heavier bullet than my 1-12, 1-9 and 1-8 twist .223's would shoot, but wanted to keep the recoil down for good sight picture and be able to shoot long strings of fire without getting the barrel hot as occurs with the BR, Dasher and .243.
At the time, a few choices I pondered were the .22 Nosler and the newer Valkyrie - both upping the .223 velocity by a solid 10%+ with heavier bullets. Just right for high-volume shooting. I chose the .22 Nosler due to the throating being better for varmint-weight bullets. I liked the two A/R's I assembled so much, I had a bolt gun built on a BAT action. I am a solid fan of the .223, but there is no contest with the faster speed of the .22 Nosler and the accuracy in my A/R's is great and the bolt gun fantastic. Even shooting a lighter bullet like a 52 grain target bullet at the much faster speeds will help a lot in conditions. Going with the heavier, high BC bullets adds to the attraction. In my opinion - it is a bit better than a .223 Ackley, plus no fireforming. Only downside is brass choices and price.
Like the .22 ARC, the .22 Nosler is lacking a diversity of brass choices - the only brass being from Nosler and "Dogtown" brass from MIDWAYUSA, which is also reportedly made by Nosler at a reduced price. The Nosler brass is priced quite high, especially compared to most brands of .223, short of Lapua. on the plus side, I have found it to be very good brass in terms of life and accuracy. The .22 ARC, at present, is the same kind of deal brass-wise. When I ordered my reamer for my bolt gun, I felt certain other manufacturers would eventually make brass for the .22 Nosler - but none so far. I'd not bet that there will be many companies making the .22 ARC brass - though it may happen. If it doesn't, you should at least consider whether being able to get various brands of brass is really important to you. Seems there is a better mousetrap out every year these days. For 300 yard targets, choosing between the .223 and .22 ARC - I'd definitely go with the ARC. One doesn't need Lapua brass to be competitive, as nice as it is. I still have a few .22 Nosler barrels for my bolt gun to shoot out, but if I were doing that build now, I'd be doing the ARC for my purposes.