While it would work, assuming your a good shot, at game not at paper, two completely different things. And you are able to pass on shots, like quartering angles that are best done with a larger Cal.
I suppose if I had a lot of time to hunt elk, and lots of elk around a guy could get by with a .243. However you have to remember, you will be passing on shots that a larger cal could be taking, and you could be tracking for a while, which would be a huge problem if you live in high country.
It will kill effectively if you can wait for a broad side shot, and somewhat close range. However, I wouldn't count on it to punch through a shoulder and then into the vitals. Which is to bad since thats a great anchoring shot.
Are you really able to accept its limitations? Personally I don't know if I could handle passing on a shot at a quartering bull because I didn't pack enough gun.