I have used the 243 a lot and I love it. But it's a deer and varmint gun. Can you kill elk or moose or whatever with a 243 sure you can. Is it recommended, I dont think so. If you got thousands of dollars invested in a hunt why would you want to take a chance with an inadequate caliber when it may be the only chance you will ever get. Doesnt make good sense.
If something bites back I want the biggest thing that I can shoot accurately.
Would you want to get in the car with someone who is to drunk to drive? You might make it you might not. Same thing if you go hunting a big brown bear with a 243 you might make it and you might become lunch
So why would you want to take that chance with your life hunting with an inadequate gun?? Especially when you can buy a cz up to about a 458 lott for about 650 to 700 dollars brand new