Boy, this string sure went along quickly. I don't own a 243 Win so I am not going to state from personal experience. Having said that there is a good article provided by this link. I think the important thing to take away is that regardless of which chamber you are going to buy, any high performance cartridge will/can cause premature barrel wear. My own experience is with military weapons and I can tell you that it is not hard to ruin a barrel by putting lots of rounds thru it too fast. In other words, not allowing the barrel some time to cool. I suspect that you are going to use this rifle for hunting and occasionally take it out to shoot at a range. In this instance I don't believe you will have any issues with barrel life (provided you don't start reloading yourself with hot loads).
I am with the crowd on the 270, great performer all around (I have a 30-06 and I would happily go with a 270).
http://www.accurateshooter.com/cartridge-guides/243win/