Consider this: Go to WalMart and see how many rounds of 7mm-08 they have. Tough to find. Which means, if you're in rural Anywhere USA and need some ammo, is the local aplliance/sporting goods store gonna have any. I know this cause I got a 7mm-08 for his first big game gun. Great round, but a bit much for plinkin'.
I'm going with the .243. I would say is the perfect "in between" round for you. Check out Federal ammo's web site and go to their balistics page and compare some of the rounds. .243 is very respectable. And is legal caliber for big game here in Wyoming.
Seems like you're comparing apples to bananna's. Those two calivers are too far apart and different to be compared.I'm getting the .243 in the Thompson Center Encore rifle, so I can get other barrels in other calibers including black powder!