The 6.5 - 284 is probably one of the most common calibres used in long range target shooting across all disciplines.The 6.5/.284 would have much better barrel life than some of the big boomers that get used in F class or 1000 yard benchrest .
It has a reputation for being hard on barrels as do most overbores. The 6BR on the other hand is not noted for this nor is the PPC. As for big boomers the average 30 cal ie 300 WM etc will get as good or better barrel life than a 6.5 - 284
The fact is if you want a light gun for long range target work the 6.5 has manageable recoil, many of the 30 cals dont so its a good choice.
Do you think that is rather a sweeping statement to make ?? do you think the differeces in general use matter ??? ie most 25's and 270's are used for hunting and are not loaded hot..a 6.5 -284 is however usually run fairly hot at long range target to get the best from the available BC.The .284 case has slightly less capacity than the .30/06 from memory . Given that then all else being equal barrel life should fit somewhere between .270 and .25/06
The 6.5 -284 is a fine cartridge and performs at long range but will chew the barrels dependant on how demanding you are of accuracy ...
cheers
Rinso