Ive used a .243 exclusively for the past 25 years, awsome caliber.
My most recent one was a Rem VLS bull barrel. I used it for about four years and couldnt get use to the weight, so I sold it. I went with a 7-08 just this year just because I wanted change, (not the Obama type ) and have made 3 kills with it, a hog a deer and a yote. So what I have seen so far the .243 seems to have left more damage. I shot a doe yesterday with the 7-08 using 139 gr Hornady btsp, it penciled in and out through the shoulder, granted the deer went 15 yds and piled up, I wasnt all that impressed. I am going to try 120 gr Bt's and see if it leaves a bigger exit. I know my .243 with 100 gr Hornady's and sierra game kings left some nasty holes.
Personaly I would get a .243 specially for a kid, my 7-08 doesnt kick much but it does kick more than the .243.