"...Swiss arms 223 are good for over 30,000 round I do believe..." Who made it makes no difference.
"...300Win is good for 2000-2500 rounds..." Way more in a hunting rifle. A heavy barreled, long range(1,000 yards/meters), target rifle is a different thing.
"...barrel life of the .223..." Barrel life is a relative thing. Mostly about accuracy. For example, benchrest shooters are looking for sub-.200" groups at 100(not using a .223.). Varmint hunters like sub-MOA groups(not shooting fast and usually heavy barrels.). Two or 3 inch groups, at 100, is good enough for deer sized game(never shooting fast nor mag loads and not with heavy barrels). All of the rifles used in those are considerably different. Barrel weights, etc. So what you intend doing with the rifle matters. Any .223 will be fun to shoot and relatively inexpensive for a centre fire. Reloading can reduce your shooting costs too.
"...this could affect headspacing..." No. Throat erosion has nothing to do with headspace in any firearm.