2muchgun, your cases bear zero relevance to this debate, I would never tell anyone that a .223 AI or not to be taking 400+ yrd shots on deer, unless your an experianced shooter your going to have more runners than killers! So your testament is a crack shot shooting at targets that the majority would be out of range for and have little energy to get the job done effectivly? 600 yards and a 5-10MPH cross wind do the math with a .223 bullet, come on get real!
A heavy barrel of what one gets factory to me is not a big deal to carry, I walk alot calling coyotes for a living I use a heavy barrel 22-250 and I just bought a heavy .243, I do have a sporter 25-06, I like it but I get far better long range accuracy with the heavy 250 and I'm sure my .243 will be the same.
If everything was killed with one shot probably not much different, except when you add in higher power scopes, recoil depending on caliber and how steady on a bi pod or sticks one can be with a heavier outfit, all this adds to better shot placement.
My only draw back to my 25-06 is I don't get to see it through the scope due to the higher recoil and lighter rifle, in many that can lead to a flinch even a slight one and shooting at 500+ yrds at a target the size of a coyote can surely lead to misses more often than a heavy barrel, one day the 25-06 will be outfitted to a remington contour heavy barrel, for now it see's less use from me than the other 2 heavy barrels, larger targets not as big a deal, I shot a 4x4 WT at 455 yards dropped stone dead, didn't see it through the scope though.
Barrel weight makes more differance in multiple shots, flinch factor and accuracy for the majority of shooters.