I was always told 264 win mag being so over bore was a barrel burner, not to expect more then 1500-2000, shots before you could expect erosion problems.. Is that not the case with the newer barrels ?
Any high intensity cartridge, regardless if it is 'overbore' or not, will have similar barrel wear within 'x' amount of rounds.
The belted mags, except the 458WM/Lott, will have very similar barrel life.
I am currently on 1422 rounds down the 26" tube in 264 for F-Class, throat erosion is at .068", another .020" or so will be expected in 3 matches or so, then it will be set back a thread or two and re-chambered.
This amount of barrel wear is no different to my other 264 barrels, 300WM barrels, 6.5-284 or 25-06. In fact, my 25-06 tends to wear more per 100 rounds than I expected. 200 rounds in and the throat extended .028"!
If you don't 'burn' a barrel up, which is shooting it until it smokes, and stop shooting when the barrel is just hot enough that you can grab it without discomfort, then barrel life will be longer than expected, even in overbore situations. My old 264 barrel is well into 3000 rounds and will still hold under MoA. I use it for culling, as a set back will no longer be viable and if it gets hot, I'm not too concerned.
Shooting 10-15 deer in a few minutes is not uncommon here. So normally we use 2-3 shooters, but I have had to do this by myself quite a few times. I also use my 25-06 for this task, barrels heat up quick.
Erosion isn't a problem, or THE problem, it's how you recognise the erosion and how you deal with it. If you keep the barrel clean of CARBON, this will drastically effect HOW the haze cracking progresses.
COPPER fouling poses less of a risk. If the bore is bright and shiny, but still shows copper streaking near the muzzle, it shouldn't pose a problem to barrel life. Barrels don't need to be SQUEAKY clean, just use a good CARBON cleaner when required and you're good to go for another 100-200 rounds with cleaning when accuracy drops away.
Cheers.