My guess is the Nosler ammo will hit the velocity they claim--at least in their rifles. There are too many chronographs out there for it not to.
My first .264 was a pre-'64 Westerner, and 3200 with 140's was possible at 65,000 psi with three powders. This was 10 years ago and only one of the powders resulted in good accuracy.
Based on some experience, I'm pretty sure deer can't tell the difference between any 100-160 grain 6.5 bullet that whacks them in the ribs. But the present 6.5 mania isn't just about killing deer, but the G1 BC, wind drift, and a range beyond 500 yards. And since deer are now killed by a new variety of statistics, many are going to judge the 26 on what it does with 140's.
