Any of these rifles are more than capable at 600 yds, as would be any new rifle choice. I have friends that successfully shoot all of these rounds at ranges past 600 yds...mostly.
All one really needs is just one rifle in just about any caliber available today that a shooter likes enough to tune it up and shoot it enough to be comfortable with it. From 243 to 338 Lapua, the fundamentals are the same.
If a shooter is not comfortable with any rifle he owns, then he has probably not shot it enough... that's the difference between a shooter and a rifleman.
If I had limited means, I would prefer to own just one rifle that I knew well, and a range finder. Owning a range finder can be as important to Long Range success as a chronograph is to the reloading process.
One can also learn mildot ranging...that requires a mil-dot scope, and is a whole 'nother level of dedication that seems to rapidly be becoming a lost art.
Back when neither were available, ranging was still a necessary fundamental skill that was done with a Duplex reticle.
An LRF will make this more convenient for the average joe, by giving the casual shooter the capability to range it, dial it and shoot, but however you do it, accurate ranging is essential and makes all calibers a lot more powerful.
