I hear people give that as a reason 6.5 creedmore is better than .260, but I load 143gr bullets in a couple .260 short action rifles and have no problems. I find it funny how the 6.5 creedmore has taken off when the .260 was already in use. Better marketing and timing (increased interest in long range shooting and hunting).The reason most people prefer the creedmoor over the 260 is it fits better in the short action than the 260 does. Other than that it's a wash between the 2. I dont disagree with what you trying to say. I'm just saying that it's not a fad and here to stay. Especially with the SOCOM adopting it as a sniper cartridge.
Anyways that's besides the point of the thread. I'll stop derailing it now
To the OP: I'd go 6.5 between those options.