The ability to fit the magazine is the exact reason I opted for the 6.5 creed.
I have read some discussions stating that the recipe printed on the Hornady Match ammo may not be the exact recipe. Some reloaders stating that when duplicated, it doesn’t provide the same velocities as the store bought version. Some have also stated, that in some Savage 12 chambers (being to tight) the Match ammo has produced high pressure signs (cratered or blown primers). This however, seems to be a Savage problem.
I really don’t think the the creed gives up much of anything. Especially if loaded with the 140’s, which is where the efficient case design shines. I’ve read alot of banter about the longer case neck allowing the 140’s to be seated farther out, increasing room for powder and at the same time keeping pressures in spec. Also the same reason you start hearing more about 260AI’s since the only way for the 260 to perform better with the 140 VLDs is to change it’s case.
Perhaps the 260 will outperform with the lighter for caliber bullets, but when it comes to 140s, the creed has the upper hand.
I also considered the 6.5×284 and just loading for about 2800fps from a 24″. Save on the barrel and brass. But there was also talk of rebarreling the 30-06 to a 6.5-06.
Lots of roads, same destination.